The advisories follow Prime Minister Samak Sundaravej's decision to impose a state of emergency overnight after clashes between pro- and anti-government protesters left one person dead and dozens injured.

The tourism industry already suffered a blow over the weekend after protesters forced the closure of three airports in Phuket, Krabi and Hat Yai. Unions sympathetic to demonstrators also shut down rail service across the country.

The airport in Hat Yai, in the country's south, reopened on Saturday only to close again Tuesday after anti-government demonstrators blocked the entrance. Protesters have also threatened action at the country's main international airport Suvarnabhumi.

'These protests are making Thailand look like unfriendly and a rather volatile place to put your money,' said Kobsidthi Silpachai, the head of capital markets research Kasikorn Bank.

'People who are probably potential tourists will say 'Hey, what is going on? There is a state of emergency issued. Maybe it's not the best place to go,'' Kobshidthi said. 'It will have a big impact.'

Singapore and South Korea issued advisories urging their citizens to postpone nonessential travel to the country. Australia and New Zealand, on the other hand, advised their citizens to 'exercise a high degree of caution' if traveling to the country.

Canadian and American authorities advised citizens to avoid demonstrations in Bangkok.

'We wish to remind American citizens that even demonstrations intended to be peaceful can turn confrontational and possibly escalate into violence,' the US Embassy warned its citizens.

'American citizens are therefore urged to avoid the areas of demonstrations if possible, and to exercise caution if within the vicinity of any demonstrations.'

Tourism in Thailand brought in about US$27 billion (S$38.6 billion) in revenue last year or about 6.5 per cent of Thailand's GDP - so a blow to the reputation of the country that promotes itself as the 'Land of Smiles' could have a ripple effect through the rest of the economy.

Thailand's economy - which is heavily dependent on tourist dollars and foreign investment - has struggled to regain its footing since a September 2006 coup ousted Prime Minister Thaksin Shinawatra.

Investors had cheered the return of democracy last year, when elections ushered in Mr Samak's government. But within months, the same protesters who helped force Thaksin from office returned to the streets to demonstrate against Samak, whom they accuse of being a proxy for the former prime minister. -- AP

Should Singaporeans require assistance, they can contact the Singapore Embassy in Bangkok or the MFA Duty Officer (24-hours) at:

Embassy of the Republic of Singapore

129 South Sathorn Road, Bangkok 10120
Tel: 001-66-(81) 844-3580
Fax: 001-66-(2) 286-6966
Email: singemb_bkk@sgmfa.gov.sg

Ministry of Foreign Affairs
Tel: 6379 8800, 6379 8855
Fax: 6476 7302
Email: mfa_duty_officer@mfa.gov.sg

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Emergency in Bangkok