The Thai government decided Tuesday to impose the Internal Security Act in Bangkok and surrounding provinces from March 11 to 23 to maintain order in the country during antigovernment demonstrations by supporters of ousted Prime Minister Thaksin Shinawatra that are expected to begin Friday.

"In view of the situation that there may be large-scale demonstrations and clashes among different groups, we have decided to raise the outward travel alert from amber to red," Security Secretary Ambrose Lee told reporters.

He urged people not to go to Bangkok and warned those who are already there to avoid places where large groups of people protesting.

A hot line is set up to offer 24-hour assistance to Hong Kong residents, Lee added.

The government was criticized for failing to send chartered flights soon enough to evacuate some 600 people who were stranded in Bangkok when antigovernment protesters took over Suvarnabhumi International Airport in November 2008.