The Nigerian Nobel prize-winning author Wole Soyinka has vowed to launch new anti-government protests after being tear-gassed and arrested by police in Lagos at the weekend.

"I was out with others to protest against the increasing dictatorship in this country," Mr Soyinka said after his release on Saturday.

He had gone out on to the streets with about 500 Nigerian human rights activists and civic leaders to protest against the government of President Olusegun Obasanjo, which they accuse of being "a civilian dictatorship".

Mr Soyinka, the leader of a pro-democracy coalition called the Citizens Forum, said he would participate in further demonstrations to press for sweeping changes, including election reforms and a new constitution.

Mr Soyinka, 69, won the Nobel prize for literature in 1986 for his autobiographical novels, poetry and plays, which depict the brutality and chaos of life under military rule.

He fled the military regime in Nigeria in 1994 and lives in the United States, where he teaches at Emory University in Atlanta.

President Obasanjo, a former military general, won elections in 1999 which ended 15 years of junta dictatorship in Africa's most populous country.

Mr Obasanjo won re-election in April last year, but the polls were dismissed as rigged by his main opponent, another former military leader, Muhammadu Buhari. Authorities earlier this month announced a ban on public demonstrations following reports of a "breach of security" which some army officials claimed was a plot to overthrow Mr Obasanjo.

In recent weeks Nigeria has seen a resurgence of religious violence.

An estimated 600 people have died in clashes between Muslims and Christians in recent weeks.

More than 10,000 people have been killed in intertwined ethnic and religious violence since 1999.

Last week Mr Obasanjo visited the ancient northern city of Kano, the site of some of the violence, and criticised some religious leaders as "idiots" for allegedly inciting the sectarian killings.