NARATHIWAT, Thailand - Security forces in Thailand's troubled south were placed on high alert for terrorist attacks yesterday after an armed gang stole a huge amount of explosives from a quarry.

About 10 men raided Manu quarry in Yala province on Tuesday night and stole at least 1,320 kilograms of ammonium nitrate, as well as 58 sticks of dynamite and 170 detonators, police said.

"Two of the quarry security guards were tied up, and there was no gun fight," officers in Yala's Muang district told AFP.

Ammonium nitrate is a fertiliser which can be made into a powerful explosive when mixed with other chemicals.

It was the main explosive used in the October 2002 Bali bombings, and 500 kilograms of the compound was seized in London Tuesday when British police arrested eight men and apparently foiled a terrorist bomb plot.

It was being used at the quarry in controlled explosions to help blast away rock, police said.

Targeting water festival

The Yala robbery heightened tensions in restive southern Thailand, where a wave of violence has swept the region since January, killing at least 55 people, mainly government officials and security forces.

Interior Minister Bhokin Bhalakula said he had instructed all security forces in the five southernmost provinces of Songkhla, Yala, Pattani, Narathiwat and Satun to go on high alert to prevent any planned attack.

He said he feared the attackers were targeting the popular tourist destination of Hat Yai in Songkhla, which will host tens of thousands of visitors during April's Songkran water festival.

"I suspect that the culprits behind this heist are aiming to strike before or during Songkran in order to terrify tourists and make a strong impact on tourism industry," he told reporters.

Senior police in Bangkok agreed Hat Yai was a target and said the attackers were stepping up their campaign following the arrests last week of nine people linked to a deadly Jan 4 raid on an army depot which kicked off the unrest.

"We do not yet know which group committed the robbery but we predict they may try to strike during the Songkran water festival (April 13-16) in crowded places like the town of Hat Yai," Special Branch police commander Lieutenant General Chalermdej Jombunud told reporters.

Mass attack

Bhokin said the robbers appeared to be intending to stage a mass terror attack along the lines of a blast in a Narathiwat nightlife district Saturday which injured 28 people including eight Malaysian tourists.

No one has claimed responsibility for the blast, the first against a civilian target since the trouble began this year, which was planted on a motorcycle in Sungai Kolok.

Prime Minister Thaksin Shinawatra has blamed the violent rampage on Islamic separatists as well as other groups, and said the culprits behind the bomb slipped into Malaysia due to red tape that delayed their arrest.

Malaysian officials in Kuala Lumpur said they were prepared to cooperate with Thai authorities but called on Thaksin to back up his charges that the attackers had crossed the border.

"If he knows who they are we are ready to act," Deputy Prime Minister and Defence Minister Najib Abdul Razak told a news conference yesterday. "We cannot take action without accurate information." - AFP