At least three people were killed and many injured Sunday in Khartoum's twin city Omdurman, as security forces threw tear gas canisters and fired live bullets at protestors during riots that swept through most of Sudan's towns.

Sudanese security forces used tear gas and sound bombs to keep protestors away from the presidential palace in central Khartoum as part of a continuing wave of demonstrations calling for a return to civil government and the army's disengagement from political space.

Thousands demonstrated in Khartoum and other towns as part of the so-called "Million of Martyrs" to demand civilian rule and denounce the death of demonstrators during last week's rallies in response to a call by resistance committees and the Sudanese Professionals Association. However, security officers confronted them when the demonstrators reached the street leading to the presidential palace.

Sudanese Professionals Association has urged doctors, surgeons, and nurses to travel to Omdurman and the capital's hospitals to treat the injured and offer required medical services.

Since Sunday morning's early hours, hybrid security forces have been deployed extensively in the capital's central business district and at the gates of the capital's three closed cities, Khartoum, Omdurman, and Khartoum North.

The US and the UN denounced the Sudanese authorities' use of "fatal" force on peaceful protestors and urged them to respect human rights and put an end to breaches.

Sudanese citizens have been protesting in the streets for more than two months against the army chief's October 25 overthrow of the civilian government, declaration of a state of emergency, and dissolution of the Sovereignty Council and Council of Ministers.

Despite excessive force against them, the demonstrators have remained resilient. Fifty-three people have been killed and hundreds injured due to live bullets and tear gas canisters fired at them.