BEIJING, April 3 -- Chief of the China Maritime Search and Rescue Center He Jianzhong said on Thursday that China is still searching for the Malaysia Airlines flight missing now for 27 days.

"Chinese vessels, as a major search force, are continuing the most difficult maritime search in history," He said.

The official said that China's search forces, including 18 vessels, eight helicopters and three fixed-wing aircraft have searched up to 200,000 square kilometers of waters since the MH370 flight went missing.

China has mobilized more than 60 merchant ships and 20 fishing boats for their assistance in the search, however, all these efforts have failed to find clues to the fate of missing flight, he said.

The center has called on vessels to enhance the search for debris underwater and maintain close communication with Australia's search forces.