Authorities in Cameroon on Thursday banned planned protest marches in the capital Yaounde after a series of unauthorised anti-government demonstrations and some 200 arrests, including the detention of main opposition leader Maurice Kamto.Former government minister Kamto, who claims to have been cheated out of the presidency in last year's elections, was arrested in the economic capital Douala on Monday.His lawyers have said he is under investigation for alleged insurrection.Four planned marches, scheduled for Friday and Saturday and the following week, are prohibited for the "preservation of public order", said area administrator Jean-Claude Tsila in a statement read out on state radio.The organisers of the marches have been asked to "give up their plans", the statement added.Opposition marches took place in several towns last weekend, protesting against the reelection of Cameroon's veteran leader Paul Biya.Biya, 85, won a seventh consecutive term in last October's disputed presidential election with 71% of the vote, according to the official results. He has held power for 36 years.Kamto came second in the election with 14%.Late on Wednesday, Kamto's lawyers said eight charges had been levelled against him and some 200 other detainees, including "group rebellion" and "hostility to the homeland".He is also accused of "insurrection", "breaching the peace" and "incitement to insurrection".All of the detainees face the same allegations, according to lawyer Sylvain Souop, member of a team of 15 lawyers."The 'facts' have been defined even before the people have been heard," he said.On Wednesday Souop met with Kamto, who was detained by an elite police unit called the Special Operations Group."He is well, his morale is good and he was interrogated (on Wednesday) in the presence of the director general of the criminal investigation division," Souop said. 'Destabilise' the government After the weekend protests, Communications Minister Rene Emmanuel Sadi accused Kamto and his party, the Movement for the Rebirth of Cameroon (MRC), of trying to "destabilise" the government. Anti-government protests also took place in some European capitals at the weekend, with Cameroonian demonstrators breaking into the country's embassies in France and Germany. In Paris, they smashed pictures of Biya and caused other damage.MRC party officials have denied organising the protests abroad."Kamto denounces this vandalism in diplomatic missions. He has never sent anyone to break anything," Souop said.A former justice minister under Biya, Kamto "has confidence in the justice of Cameroon", Souop said.Other people detained by the authorities include MRC activists and the party treasurer Alain Fogue.Security forces also arrested two Cameroonian journalists on Monday night, confusing them for political activists, according to the national journalists' union.Both men were still in detention on Thursday.Press freedom watchdog Reporters Without Borders on Thursday said a journalist was assaulted "by three unidentified individuals as he was leaving his house" but did not specify whether the attack was related to his work. 'Escalating crackdown' In a statement on Thursday, the National Council of Communication (CNC) said it had noted a rise in "calls for sedition or incitement to tribal hatred" in the media and on social networks.The CNC "calls on all those involved in the media sector to show professionalism and responsibility in the collection, processing and dissemination of information intended for the public", wrote CNC president Peter Essoka.Human rights groups have condemned Kamto's arrest and called for his immediate release.Analysts say the authorities view Kamto as a threat."It's been a long time since Cameroon had an opposition figure of this stature," Hans de Marie Heungoup from the think tank International Crisis Group told AFP in Libreville.Sign up to News24's top Africa news in your inbox: SUBSCRIBE TO THE HELLO AFRICA NEWSLETTERFOLLOW News24 Africa on Twitter and Facebook.