Four soldiers were killed on Sunday during a brazen arms robbery by dozens of assailants, as 18 schools were set ablaze in Narathiwat and Yala provinces.
On Monday, martial law was declared in some districts after two bomb blasts killed two policemen.
On Tuesday, military bomb disposal experts were called to a shop in downtown Pattani near a large mosque after it received a telephone threat, but were yet to arrive from neighbouring Yala.
"Someone telephoned in a bomb threat about an hour ago," Police Sergeant Nisoh Sahdee told AFP, as several soldiers wielding M-16s milled around the shop, awaiting experts and police.
"It is a similar situation (to Monday) that we have here," he said, in another indication of the growing climate of nervousness in the region.
Local reports said eight schools in Pattani had cancelled classes due to bomb threats, but local authorities had found nothing irregular.
"As of now we still do not know who the culprits were, but based on evidence we obtained and (which was) examined by forensics, the bombs were new models and I think that the culprits will create more unrest," deputy prime minister Chavalit Yongchaiyudh told reporters before leaving Bangkok.
He rushed to Pattani with Interior Minister Wan Muhammad Nur Matha, the only Muslim minister in government Defence Minister Thammarak Issarangkul Na Ayutthaya and army commander General Chaisit Shinawatra early on Tuesday.
"The three ministers and the army commander have received a briefing from the military, police and top civil officials in Pattani," Major General Jiarapan Kasemsansuk told AFP.
Pattani is one of five majority-Muslim provinces in southern Thailand, which has seen a spate of violent attacks against police and the military, including the killings of 20 people since April 2003.
A man searches through a
torched school following an attack
Thai Prime Minister Thaksin Shinawatra told reporters he was worried about the violence, blaming a weak bureaucracy for failing to anticipate and quash the attacks.
"Absolutely, I am so worried over what has happened. We have to tackle it and we have to achieve this goal. Nothing is easy," he said.
Interior minister Wan Nur said he had instructed officials in the south to boost security at government offices, schools, community gathering places and entertainment spots.
"They should provide 24-hour security protection to all these
places," he said, adding that the assailants included drug addicts and the unemployed.
Thaksin on Monday dismissed suggestions that separatists were behind the two days of violence, but conceded that Islamist dissidents had been at work in the area. A separatist rebellion has simmered for years in Thailand's deep south.
"As of now we still do not know who the culprits were, but based on evidence we obtained and (which was) examined by forensics, the bombs were new models and I think that the culprits will create more unrest"
Chavalit Yongchaiyudh, Thai deputy prime minister
A district civil officer, Niporn Narapitakul, said the city was unperturbed by the ongoing threats, as security did not appear to be overly tight.
"It is normal. There's a little bit of fear but not too much,
this happens every year," he said. Defence ministry spokesman major-general Palangoon Klaharn said the Fourth Army, which is responsible for security along Thailand's border with Malaysia, would use troops in the region if required.
"The local army will mobilise troops from the regional Fourth
Army rather than sending them from here (Bangkok)," he told reporters.
Martial law has been declared in several districts in Pattani,
Yala and Narathiwat provinces, giving soldiers the power to detain suspects without warrants and seize property.