Singaporeans should still avoid non-essential travel to Bangkok, The Ministry of Foreign Affairs (MFA) said after anti-government protesters agreed Tuesday to end their blockade of the Thai capital's airports.

"Although there have been reports that Suvarnabhumi Airport will re-open to incoming flights, the Ministry of Foreign Affairs would like to reiterate its earlier advisory to Singaporeans to postpone non-essential travel to Bangkok," the ministry said in a statement late Tuesday.

It said it was closely monitoring the situation.

The statement came before a senior official of the Airports of Thailand agency said international flights from the main Suvarnabhumi airport are to resume Thursday night.

Protesters began leaving Suvarnabhumi on Wednesday after agreeing to end their eight-day blockade that has stranded hundreds of thousands of international travellers unable to leave from Suvarnabhumi or the older Don Mueang airport in Bangkok.

Foreign nations including Singapore have sent emergency flights to evacuate their citizens.

Singapore-based airlines have been among those using the Vietnam War-era U-Tapao military airport southeast of Bangkok. They have also put on additional flights to the Thai cities of Phuket and Chiang Mai, which were not blockaded.

MFA said it has helped 490 Singaporeans leave Thailand through U-Tapao or the two other cities, leaving about 120 still in Bangkok.

Singapore Airlines' two daily flights from U-Tapao could be continued beyond Wednesday, while SilkAir is operating additional flights to Phuket until Sunday, the ministry said.

SilkAir will also put on extra flights to Chiang Mai, while another Singapore-based airline, Tiger Airways, will continue its extra flights from Phuket, the ministry added.