The ambassadors of the United States, European Union, Australia, Canada, Japan, South Korea and New Zealand also called on all sides in Thailand's political crisis not to threaten airport operations again.
In a joint statement, the envoys welcomed the end of an eight-day blockade but said it was 'most regrettable and highly inappropriate' that protesters had been able to seize Suvarnabhumi international and Don Mueang domestic airport.
'We urge the government of Thailand to take all necessary measures to improve the protection and security of all Thai airports, so as to avoid the recurrence of a similar seizure in the future,' the statement said.
The ambassadors also called on 'all sides concerned not to threaten the operations of Suvarnabhumi and Don Mueang airports and to commit themselves not to disrupt air traffic either in Bangkok or at regional airports.' Thai officials have said more than 350,000 travellers were stranded by the protests.
Protesters from the People's Alliance for Democracy left the airports on Wednesday, a day after Thailand's constitutional court barred premier Somchai Wongsawat from politics for five years and disbanded the ruling party.
They have warned of further protests if the new premier is too close to Thaksin Shinawatra, the exiled former prime minister who was ousted in a military coup in 2006. -- AFP