Seven leaders of anti-government protests have been summoned by Thai police to face charges of lese majeste over comments made at demonstrations demanding reforms to the monarchy, a police source and a rights group said on Tuesday.

It will be the first time in more than two years that such charges have been brought under the so-called lese majeste laws concerning insults to the royal family. They can spend up to 15 years in jail.

Protests against Prime Minister Prayuth Chan-Ocha that began in July have increasingly turned to demands to curb King Maha Vajiralongkorn's powers, breaking a long-standing taboo to criticize the monarchy.

The police source, who declined to be named because he was not permitted to speak to the media, said the leaders of the protest had until Nov. 30 to reply to the summonses made at the protests on Sept. 19 and 20.

One of the seven, Parit "Penguin" Chiwarak, told Reuters that a summons on the charges had been received by his family and he was not worried.

"This will reveal to the world the brutality of the Thai feudal system," he said. "We'll continue to fight."

Others named included human rights lawyer Arnon Nampa, who on Aug. 3 became the first to call for royal reforms, and Panusaya "Rung" Sithijirawattanakul, a student leader who laid down 10 royal reform demands.

Neither was available for comment immediately.

Thai Human Rights Lawyers told Reuters that police had notified the lawyers of the protest leaders.

The summonses came a day before the protesters said that they would march to the royal fortune management office to demand that the king give up personal control of the assets.

On Tuesday, police said no protesters would be permitted within 150 meters (450 feet) of the Crown Property Bureau, where royalists also said they were planning to gather in defense of a monarchy facing its greatest challenge in decades.

More than 50 people were injured last week when, on the most violent day of more than four months of demonstrations, the police used water cannons and tear gas against thousands of protesters in parliament.

The reversal of changes that gave the king personal control over a royal fortune valued at tens of billions of dollars is among the demands of the protesters.

In a Twitter post, the FreeYouth protest group said they would demonstrate on Wednesday to "reclaim the property that is intended to belong to the people."

Since the protests began, the Royal Palace has made no comment, although the king said that the protesters were loved "all the same" when asked for comments on the demonstrations.

Prayuth rejected the calls of the protesters to resign and said last week that all laws would be used against protesters who break them - raising activists' concern that among them would be the royal insult laws.