Thai officials are addressing ways to tackle the growing tide of violence in the south of the country, near the Malaysian border.

Two policemen were shot and killed as they escorted a bus full of teachers in the latest attack on Wednesday.

We must take tougher measures to stop this

Prime Minister Thaksin Shinawatra

Two days earlier a bomb exploded on a train injuring a policeman and a guard.

Some 14 policemen have been killed so far this year in the region, where Muslim insurgents seeking independence were active in the 1980s.

Prime Minister Thaksin Shinawatra said he feared more violence in the area, but did not link the attacks on police officers to religion, the Reuters news agency reported.

"There could be more incidents, but we must take tougher measures to stop this," he said.

"I don't think religion was the cause of the problems down there because several of the policemen killed were Muslim."

Drugs link suspected

Interior Minister Purachai Piemsomboon visited the scene of the latest shootings in Sungai Padi, about 800 kilometres (500 miles) south of Bangkok.

He said drug traffickers were suspected as being responsible for the violence.

"They are looking after their own interests, they are motivated only by money," he said in a television interview.

"This is happening because police are making serious efforts to make arrests over drugs trafficking."

Earlier, police chief General Sant Sarutanond agreed that the separatist groups that plagued the area in the 1980s were not suspected of the attacks.

"It must be a bandit group but not terrorists," he said.

No-one has claimed responsibility for the attacks in Sungai Padi, in Narathiwat - one of five Thai provinces bordering Malaysia where Muslims are in the majority.