Domestic Thai airlines have started moving equipment back to Bangkok's old Don Muang airport, which is set to reopen for commercial flights.

Flag carrier Thai Airways International and two budget airlines - Nok Airlines and One-Two-Go - are scheduled to resume domestic flights from Don Muang on March 25, six months after it was shut and all commercial flights were moved to the new Suvarnabhumi Airport.

International connections will continue to use the new airport in a bid to minimize inconvenience for the 40 million passengers expected to fly through Bangkok this year. Thai Airways' flights to holiday hotspots like Phuket and Chiang Mai will also remain at Suvarnabhumi.

Officials estimate that making Don Muang a domestic hub will relieve almost 20 percent of the traffic at Suvarnabhumi, which has faced lingering problems since opening September 28, 2006.