A month after Malaysia Airlines MH370 vanished, the search for the plane continues despite statements from authorities that no one aboard survived.

The Boeing 777-200 aircraft carrying 227 passengers, including 154 Chinese, and 12 crew members disappeared on March 8 while flying from Kuala Lumpur to Beijing.

Since then, China, along with more than 20 other countries, has joined the unprecedented international hunt for the plane.

No definitive signs of the plane have been found so far, but the search goes on as the aircraft's black box continues to run out of battery, complicating the search.

"I'm anxious," said a young woman, a close friend of a 25-year-old passenger on board the plane, adding that she hopes the black box will be retrieved soon.

"Otherwise there may be no chance for the truth to be restored," she said.

A MISSION OF HOPE AND UNCERTAINTY

The Malaysian jetliner is believed to have crashed in the southern Indian Ocean, although no confirmed debris has been found.

On Tuesday, 11 military planes, three civil planes and 14 ships assisted in the search for MH370, the Joint Agency Coordination Center (JACC) for the international search effort said in a media release.

The search area is about 77,580 square kilometers, and good weather is expected throughout the day.

According to the JACC, the underwater search continues with Australian vessel Ocean Shield at the northern end of the defined search area and Chinese ship Haixun 01 and the British HMS Echo at the southern end.

Pulse signals consistent with those from an aircraft black box were detected by Ocean Shield and Haixun 01 over the weekend in separate locations at a depth of 4,500 meters.

But further confirmation is needed as to whether the signals are related to MH370.

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

Vessels from China's ministry of transport searching for the missing jet had searched an area of 145,479 square kilometers by midday 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.