France strongly urged its citizens in Bangkok 'to stay in their homes or hotels' and recommended postponing of non-essential travel until calm returns.

South Korea called on its nationals in Bangkok and the seaside town of Pattaya 'to return home if they are not on urgent matters.'

A weekend summit of 16 Asian leaders in Pattaya, about 100 kilometres south of Bangkok, was canceled after protesters stormed the venue and leaders were evacuated by helicopter.

Soldiers in combat gear moved into several parts of the Thai capital Monday firing automatic weapons, mostly into the air.

Despite the crackdown, authorities appeared unable to disperse protesters, who are demanding the resignation of Prime Minister Abhisit Vejjajiva. There were initial reports of dozens injured.

The US Embassy issued a warden message urging Americans 'to avoid the areas of demonstrations and to exercise caution anywhere in Bangkok.'

Australia advised its citizens to reconsider traveling to Bangkok or surrounding provinces, and to 'exercise a high degree of caution because of the political instability in Thailand and the possibility of political demonstrations.'

'The Australian government is deeply concerned at developments in Thailand,' Foreign Minister Stephen Smith told reporters. 'We urge the political leadership in Thailand to resolve these matters peacefully and in accordance with the law.'

Britain also told citizens to 'urgently review' travel plans to the Southeast Asian nation and 'to avoid any areas where demonstrations are taking place and to stay indoors as far as possible.' -- AP