Chinese vessels would enhance underwater search for the Malaysian flight MH370, now missing for 31 days, said a senior Chinese maritime official on Monday.

Chief of China Maritime Search and Rescue Center He Jianzhong called upon Chinese search forces to increase communication with Australian counterparts and coordinate search operations under water, on ocean surface and in the air.

Vessels of China's ministry of transport searching for the missing passenger jet had searched areas of 145,479 square kilometers by midday of Monday, according to He, also vice minister of transport.

By midday Monday, the center had mobilized 62 merchant ships for assistance in the search, he said.

China has made all-out efforts to search for the missing plane using 18 vessels, eight helicopters and three fixed-wing aircrafts.

The Malaysia Airlines flight bound for Beijing from Kuala Lumpur disappeared on March 8 and more than 20 countries have gathered to work out its fate. No definitive signs have been found so far.