Shoppers were advised not to enter malls wearing sunglasses and baseball caps -- a disguise used by insurgents -- to ensure they are not confused with "the bad guys," said Col. Sansern Chaengkamnerd, a military spokesman.

Intelligence officials did not say whether they had specific information about planned attacks but reiterated comments from last week that special precautions would be taken ahead of Makha Bucha, a Buddhist holy day, on March 3.

The holiday celebrates Buddha's first sermon to a spontaneous gathering of 1,250 of his adherents. It is typically a busy period at shopping and religious sites.

The Internal Security Operations Command, a counterinsurgency agency, has ordered all security forces "to be on full alert for the upcoming Makha Bucha day," said the ISOC secretary general Montri Sangkasab.

Bangkok Gov. Apirak Kosayothin spent the weekend inspecting some of the city's major shopping malls to ensure that security guards were aware of the heightened measures and that closed-circuit cameras were in working order, said his spokesman, Chanin Rungsaeng.

More than 2,000 garbage bins have been replaced with transparent bags to ensure bombs cannot be hidden inside, he added. Security officials were also inspecting bags of people entering the shopping complexes.

Concerns about attacks were spurred by a wave of bombings Feb. 18 in Thailand's restive southern provinces as thousands were celebrating Lunar New Year. About 30 coordinated bombings, arson and shooting attacks were carried out and officials said insurgents were trying scare ethnic Chinese Buddhists celebrating the holiday.

Defense Minister Gen Boonrod Somtad subsequently warned that insurgents could extend their attacks to the capital, prompting the Australian, British and Canadian embassies last week to update their travel warnings about possible terrorism in Bangkok.

The separatist insurgency, which has claimed about 2,000 lives in the past three years, has been largely confined to Thailand's three southernmost Muslim-dominated provinces that border Malaysia.