Citing safety concerns highlighted by an international audit, the agency late in March imposed a ban on Thai airlines from operating new charter and scheduled services to Japan.

Nearly 120,000 travellers seeking to go to Japan on flights operated by national carrier Thai Airways International (>> Thai Airways International PCL), as well as long-haul, low-cost carriers like Thai AirAsiaX and NokScoot, had been expected to be affected by the ban.

Under the provisional lifting of the ban, airlines are not permitted to change the type of aircraft they have indicated they will operate, Prajin said at a news conference in Bangkok.

Scheduled flights to Japan will continue to operate as normal, he said.

Thailand's Department of Civil Aviation (DCA) aims to complete on April 10 the re-evaluation of six airlines' licences and will send the finding to Japan's civil aviation agency, Voradech Hanprasert, deputy permanent secretary at the Thai Transport Ministry, told a separate news conference.

The six included Thai Airways, Thai AirAsiaX, NokScoot, Jet Asia Airways, Asia Atlantic Airlines and Asian Air.

NokScoot, a joint venture between Nok Airlines (>> Nok Airlines PCL) and a Singapore Airlines (>> Singapore Airlines Ltd.) subsidiary, is expected to be most affected given it needs to delay launch of new scheduled flights to Japan, Voradech said.

The safety concern was raised in late March during an audit of DCA by the Montreal-based International Civil Aviation Organization (ICAO), which gave DCA a 90-day grace period to comply with international standards.

Voradech said DCA has to improve its operations to meet a deadline in June, while Thai authorities will speed up the restructuring of DCA and the amendment of regulations by October.

Over the next two months, DCA will also re-evaluate all 41 licences it granted to airlines, starting with 28 carriers flying international routes to ensure that its operations are in line with ICAO standards, Prajin, the Thai transport minister, said.

Thailand has struggled for almost a decade to comply with ICAO standards, the minister has said.

(Editing by Kenneth Maxwell and David Holmes)

By Khettiya Jittapong and Manunphattr Dhanananphorn