China has deployed more than ten vessels and 21 satellites to search for the missing Malaysia Airlines jetliner with 239 people on board, including 154 Chinese.

"More than ten search vessels from China are searching in the related seas. We have deployed 21 satellites, informed 25 countries of the development and asked them for help," Foreign Ministry spokesman Hong Lei told a daily press briefing on Tuesday.

Hong said China appreciated those countries' all-out efforts to help with the search.

"As long as there is a glimmer of hope, we will make unremitting efforts," Hong said, acknowledging the search area has significantly expanded.

China has used satellites and radars to search for the missing jet in parts of its own territory covered by a northern corridor that the aircraft could have flown through, Hong said.

Malaysian official sources say the plane could be anywhere along a giant arc extending from Kazakhstan in the north to the Indian Ocean in the south.

China said on Monday that the focus of its search was no longer just in the South China Sea.

Hong called on Malaysia to provide comprehensive and accurate information regarding the search area and come up with solutions.

"We believe search and investigation should go hand in hand," as the investigation can offer more accurate and all-round information for the search, Hong said.

Hong said China has closely coordinated with Malaysia. "As long as the work helps with the search, China will actively coordinate."

By Tuesday, 26 countries were searching for the plane, compared with 14 last week. China has updated its embassies in the countries on latest developments.

(Xinhua News Agency March 18, 2014)