Four masked youths tossed gasoline bombs at a McDonald's restaurant in the conflict-torn city of Oaxaca before dawn on Sunday, damaging the store's windows, seats and play area, police said.

Security personnel at the shopping center where the McDonald's is located were able to extinguish the blaze and there were no injuries, said state police director Manuel Moreno Rivas, citing witness reports.

The shopping mall is near a university where leftist protesters set up their headquarters last month after police drove them out of city's main plaza, which they had occupied since May in a bid to force the resignation of the Oaxaca state governor. Those activists attacked a Burger King restaurant in the same mall with gasoline bombs last week.

Leaders of the movement, known as the Oaxaca People's Assembly, denied their members were responsible for Sunday's attack.

McDonald's was at the center of controversy here in 2002, when artists and community groups forced the chain to abandon plans to open a franchise in Oaxaca picturesque colonial main square, saying it would hurt the city's cultural identity.

A public relations firm representing McDonald's in Mexico issued a statement saying a police complaint was filed following the attack and noting the restaurant was back in operation later in the day.

"At McDonald's we respect freedom and the right to voice opinions, as long as this is done peacefully, but the safety of our employees and customers is our highest priority," the statement said.

Oaxaca's conflict started as a teachers' strike for higher pay. It expanded into a fight to oust Gov. Ulises Ruiz, with leftist protesters seizing the city center, building barricades, burning buses and taking over radio stations to call for revolution.

The unrest has driven foreign tourists away from the city, one of the country's top attractions.

Late last month, President Vicente Fox sent 4,000 federal police to take the city center, but the violence persisted elsewhere as officers with water tanks and riot gear clashed with protesters using gasoline bombs and fireworks packed with glass and nails. Last week, 30 people were injured in the confrontations.

There have been at least nine political killings in Oaxaca city since August, mostly of Sosa's supporters. The movement accuses Ruiz of sending armed thugs against them and rigging his 2004 election.

Sunday's attack came a day after the Roman Catholic bishop of Oaxaca declined a request to give asylum or sanctuary to People's Assembly leaders who fear arrest.

Bishop Jose Luis Chavez Botello said the church is trying to facilitate understanding and dialogue and has not taken sides in the conflict.

The movement's most visible leader, Flavio Sosa, faces arrest warrants on riot and conspiracy charges and says he has not slept at home in months.

Sosa has engaged in sporadic talks with the federal government and frequently speaks to reporters and supporters just blocks away from positions taken by the federal police, who apparently have not pursued him.

Also Saturday, a convention of the People's Assembly met to plan the movement's strategy, after striking teachers voted to accept pay increases and many agreed to return to work.