MANAMA, Jan 21 (Reuters) - Saudi Gulf Airlines is set to obtain regulatory approvals to launch flights within the kingdom by the end of March, a top official at Saudi Arabia's aviation watchdog said on Thursday.

Should the licence be granted to the privately-owned airline, it would be the first to be awarded under plans to liberalise the kingdom's aviation market.

"We expect them to fly end of March, early April," Abdulhakim Altamimi, assistant president for safety, security and air transport at the General Authority of Civil Aviation (GACA), told Reuters on the sidelines of the Bahrain Airshow.

Only national carrier Saudi Arabian Airlines and budget operator National Air Services currently serve a domestic market of about 27 million people. Foreign carriers can only fly in and out of Saudi Arabia and not within the country.

The Saudi authorities began accepting applications to operate internal flights back in 2012, although the process of granting licences has been slow: Qatar Airways, through its subsidiary Al Maha Airways, was one such applicant but red tape has delayed its launch.

Saudi Gulf Airlines' launch has also been delayed. It had hoped to commence operations last November with four A320 single-aisle planes.

The carrier is now in the final regulatory stages of checking manuals for standard operating procedures and flying the necessary 100 hours with a GACA inspector, Altamimi said.

Owned by the Abdel Hadi Al-Qahtani & Sons group, Saudi Gulf Airlines plans to fly from Dammam to Jeddah, Riyadh and Dubai, Samer Majali, the group's president and senior adviser, told Reuters in a separate interview at the airshow.

He added the airline would start operations soon after the licence was granted.

(Reporting by Nadia Saleem; Editing by David French and Mark Potter) ((davidj.french@thomsonreuters.com; +971 4 362 5864; Reuters Messaging: davidj.french.thomsonreuters.com@reuters.net))