After a deadly three-month siege in Mariupol, Moscow captured Ukrainian combatants, and a separatist commander backed by Russia has sworn that they will face trials. This is causing growing concern among Ukrainians.

Russia has claimed full possession of the Azovstal steel mill, the final Ukrainian stronghold in Mariupol, and a symbol of Ukrainian fortitude in the important port city, which is now in ruins. More than 20,000 civilians are thought dead.

It gives Russian President Vladimir Putin a desired win in the conflict he launched in February.

According to his office, Polish President Andrzej Duda has arrived in Ukraine on an unannounced visit and will address the country's parliament on Sunday.

Poland, which has taken in millions of Ukrainian refugees since the war, strongly supports Ukraine's desire to join the European Union.

Due to Russia's blockade of Ukraine's seaports, Poland has become a significant entry point for western humanitarian aid and armaments entering Ukraine. It has assisted Ukraine in exporting its grain and other agricultural products to international markets.

After reporting that its forces had eliminated the final holdouts from the steel plant's miles of underground tunnels, the Russian defense ministry published video footage of Ukrainian soldiers being arrested.

The warriors' family members, who hailed from a variety of military and law enforcement groups, have begged for them to be granted prisoner of war rights and ultimately returned to Ukraine. Saturday, Deputy Prime Minister Iryna Vereshchuk stated that Ukraine "will fight for the return" of each individual.

Denis Pushilin, the pro-Kremlin leader of a region of eastern Ukraine controlled by rebels backed by Moscow, stated that 2,439 individuals were detained.

He stated on Russian state television that the number includes some international nationals but did not disclose any other information.

"In my opinion, justice must be restored. Mr. Pushilin was quoted by the Russian state news outlet Tass as saying, "There is a demand for this from ordinary people, society, and probably the same portion of the global community."

On Friday, buses escorted by Russian armored vehicles left the factory.

According to Russian authorities, at least some Ukrainians were sent to a former prison colony, while others were reportedly hospitalized.

The Kremlin has exploited the far-right origins of the Azov Regiment to portray its invasion of Ukraine as a war against Nazi influence.

For weeks, the Ukrainian government has not reacted to Russia's allegation that it has captured Azovstal, the last Ukrainian stronghold in Mariupol.

The Ukrainian military informed the fighters that their task had been accomplished and that they could leave. Their extraction was depicted as an evacuation, not a mass surrender.

The conclusion of the battle for Mariupol would help Mr. Putin recover from some severe failures, such as the inability of Russian troops to seize Kyiv, the loss of the Russian Navy's flagship in the Black Sea, and the ongoing opposition that has halted an attack in eastern Ukraine.

It also advances Russia's goal of creating a land bridge from Russia to the Crimean Peninsula, which Moscow annexed from Ukraine in 2014.

The effect on the war as a whole remained unknown.

Numerous Russian troops had already been redeployed from Mariupol to other war zones.

Igor Konashenkov, a spokesperson for the Russian defense ministry, stated on Saturday that Russia had destroyed a Ukrainian special-operations base in the Black Sea province of Odesa and a large cache of western-supplied weapons in the northern Ukrainian region of Zhytomyr. No confirmation was received from the Ukrainian side.

The Ukrainian military reported intense battle in parts of eastern Ukraine's Donbas region.

In his nightly video address to the nation, President Volodymyr Zelensky stated, "The situation in Donbas is tough." The Russian army attempts to invade Sloviansk and Sievierodonetsk as it has in previous days.

He stated that Ukrainian forces thwart the onslaught "every day."

Sievierodonetsk is the principal Ukrainian-held city in the Luhansk area, which, along with the Donetsk region, comprises the Donbas. The only operating hospital in the city, according to Governor Serhii Haidai, has only three doctors and supplies for ten days.

On Sunday, the British Ministry of Defense reported that Russia's only operational company of BMP-T Terminator tank support vehicles, designed to defend main battle tanks, "has likely been deployed to the Sievierodonetsk axis of the Donbas offensive."

With a maximum of 10 vehicles deployed, it was stated that "they are unlikely to have a significant impact on the campaign."

Sloviansk, located in the Donetsk area, is crucial to Russia's goal of seizing all of eastern Ukraine, and it was the scene of fierce combat last month when Moscow's soldiers withdrew from Kyiv. The governor reported that the Russian bombardment on Saturday killed seven civilians and injured ten others across the province.

Mr. Zelensky emphasized that the Donbas is still a part of Ukraine and that his men are fighting to free it.

During a joint press conference with Portuguese Prime Minister Antonio Costa, Mr. Zelensky urged western nations to provide Ukraine with multiple-launch rocket systems and "just standstill" in other countries despite being crucial to Ukraine's prosperity.

Saturday, US President Joe Biden approved a fresh infusion of $40 billion (£32 billion) in aid for Ukraine, of which half is for military assistance.

Portugal has offered up to 250 million euros (£211 million) and ongoing military equipment shipments.

Mr. Zelensky reaffirmed his desire to petition for membership in the European Union and accused Russia of obstructing agricultural exports from Ukraine, the "breadbasket of Europe."

Mariupol, a city in the Donbas, was blockaded early in the conflict and provided a horrifying example for the rest of the country of the starvation, fear, and death they would experience if the Russians surrounded their villages.

The coastal steelworks, including around four square miles, served as a battleground for weeks.

With the assistance of airdrops, the diminishing band of outgunned Ukrainian fighters withstood Russian aircraft, artillery, and tank fire.

Mr. Zelensky disclosed in an interview released on Friday that Ukrainian helicopter pilots braved Russian anti-aircraft fire to transport medication, food, and water to the steel factory and remove bodies and rescue wounded fighters.

He stated that a "very large" number of the pilots perished during the missions, calling them "absolutely heroic."

Saturday, the Russian Ministry of Defense released a video showing Russian troops arresting Serhiy Volynskyy, commander of the Ukrainian Navy's 36th Special Marine Brigade, which was one of the primary forces defending the steel complex.

The Associated Press has not independently confirmed the video's date, location, and conditions.

With Russia in control of the city, it will be difficult for Ukrainian authorities to document alleged Russian atrocities in Mariupol, such as bombing a maternity facility and a theater where hundreds of civilians had taken shelter.

In April, satellite imagery revealed what seemed to be mass graves just outside Mariupol, prompting local officials to accuse Russia of hiding the carnage by burying up to 9,000 individuals.

An estimated 100,000 of the 450,000 people who lived in Mariupol before the war still dwell there.

Due to Russia's siege, many people were left without food, water, and electricity.

Saturday, the mayor of Mariupol, Ukraine, warned that the city faces a "catastrophe" in public health and sanitation due to mass burials in shallow graves around the damaged town and the collapse of sewage systems.

Vadim Boychenko warned that summer rains could contaminate water sources as he urged Russian forces to permit inhabitants to evacuate the city safely.

"In addition to the humanitarian disaster created by the (Russian) occupiers and collaborators, the city is on the verge of an infectious disease outbreak," he added via the messaging app Telegram.