KUALA LUMPUR (AFP) - A Malaysia-bound Malindo Air flight diverted to Thailand and made an emergency landing on Monday after the cabin started to de-pressurise, the airline said, adding that none of the 129 people aboard was hurt.

The Malaysia-based carrier's flight OD206 from Delhi had been due to arrive in Kuala Lumpur early Monday but instead re-routed to Bangkok after the incident, which caused oxygen masks to deploy inside the plane.

"A slow decompression was detected by the pilot," said a Malindo spokesman, who suggested it may have been caused by oxygen leaking from the fuselage.

"In our case, oxygen masks were deployed as a precautionary measure according to SOP (standard operating procedure)." The Boeing 737-900ER had 121 passengers and eight crew aboard.

The incident was still being investigated.

Malindo Air, which commenced operations last year, is a joint venture between Malaysian and Indonesian companies.

In March, a Malindo Air flight bound for Kuala Terengganu from Subang was turned around after one of its engines caught fire midway through the flight.

Malaysian aviation has endured a horrible year with flag carrier Malaysia Airlines losing two jets and 537 people.

Flight MH370 disappeared in March with 239 people aboard and is believed to have mysteriously diverted and crashed in the southern Indian Ocean, but no evidence to prove the theory has been found.

Flight MH17 came down over conflict-torn Ukraine in July, believed to have been shot down by a surface-to-air missile, killing all 298 people aboard.