The early relocation, two weeks ahead of the airport's controversial Sept 28 opening, would pose serious problems for connecting passengers as all international flights would remain at Don Muang, it said.

Virtually every domestic flight had passengers linking to outbound international services while incoming international arrivals also have passengers who need to connect to domestic flights, the union said.

This meant connecting flights would be missed and the airline would have to take responsibility for hotel and other expenses.

"If the government insists on opening the new airport for domestic service on September 15, we will ask employees not to report to work at Suvarnabhumi Airport on that date," a union official said.

The union said it would send an urgent note to Transport Ministry permanent secretary Wanchai Sarathulthat to try to clarify the early relocation date.

"Most THAI employees learned of the plan from the news media," said another union official, who noted that the idea - unveiled by caretaker premier Thaksin Shinawatra during his weekly radio address last week - could lead to serious technical problems for THAI aircraft.

For instance, he said the maintenance staff would not be able to fix any technical problems in the THAI fleet because most spare parts would still be at Don Muang. And at present, most of the parts and equipment for repair were shared among aircraft for both domestic and international flights.

THAI would also not be able to maximise the use of its cabin crew and pilots because it would be impossible to connect transit flights between international and domestic flights when using two airports.

International passengers and related parties have also not been fully informed of the early relocation plan, he said. Most were not aware of which airport they have to go to because at present the code is only "BKK" for Bangkok.

Thus, the union had asked airline managers to urge the government to review the early relocation plan - to protect the interests of THAI and its passengers, he said.

Transport Minister Pongsak Ruktapong-pisal insisted yesterday that THAI would start domestic flights from Suvarnabhumi on Sept 15, but said other airlines may move to the new airport when ready.

THAI president Apinant Sumanaseranee said the airline would only fly three domestic routes from Suvarnabhumi on Sept 15 - to Phitsanulok, Ubon Ratchathani and Chiang Mai.

Thaksin said yesterday that the early relocation plan would help the new airport reduce the chaos expected on September 28 when international and domestic services both begin operations.