BEIJING, March 23 (Reuters) - The Chinese aviation regulator has launched a sector-wide inspection for potential safety lapses as authorities race to search for victims and the black boxes of a commercial jet that crashed in the mountains of southern China.

The cause of the crash of the China Eastern Airlines jet in Guangxi region on Monday (Mar 21) is yet to be determined, with Chinese aviation authorities warning that their investigation would be very difficult because of the severe damage to the aircraft.

The two-week inspection of the sector will involve checks at all regional air traffic control bureaus, airline companies and flight training institutes to ensure the "absolute" safety of aviation operations and people's lives, the Civil Aviation Administration of China (CAAC) said late on Tuesday.

Since the crash, China Eastern and two subsidiaries have grounded their fleet of more than 200 Boeing 737-800 jets. The last commercial jetliner to crash in mainland China was in 2010, when an Embraer E-190 regional jet flown by Henan Airlines went down.

Highlighting the top-level concern, Vice Premier Liu He went to Guangxi on Monday night to oversee search-and-rescue operations. A vice premier was similarly sent to the site of the crash in 2010.

Officials in charge of the search and rescue are going "all out in their search as long as there is a glimmer of hope," after a special meeting on Tuesday helmed by Liu, according to state media reports.

Officials were also told to release information "in accordance with the principles of timeliness, accuracy, openness and transparency", and the broader aviation sector must carry out special checks to prevent the occurrence of major safety accidents.

At the first news conference held by the government late on Tuesday night in Guangxi, an aviation official said the 737-800 jet that crashed had met airworthiness standards before take-off and crew members had been in good health.