The gunmen shot two police officers as they shopped at the market in Yala province then killed a paramilitary officer at the scene who opened fire in retaliation, district police officer Sarawoot Mahardchai said.

"The killers were walking with villagers at the market before they started shooting at the policemen," he told AFP.

"It seems like the attackers especially targeted the policemen," said Sarawoot. "We believe that they are suspected Muslim militants trying to worsen the violence and unrest in the south."

Education Minister Chaturon Chaisaeng said that more than 100 schools in Yala would be closed for one week starting from Monday due to security concerns.

"We are aware that teachers have become the main target of the attacks in the south," said the minister who is due to visit Yala on Thursday to discuss safety measures.

Prime Minister Thaksin Shinawatra, who has been criticised for failing to quell the violence in the south, said he would go there to evaluate the situation following his current trip to the northern city of Chiang Mai.

"When I finish the mission in the north, I will follow (Justice Minister) Chidchai Vanasatidya to the south," he said.