PHNOM PENH, March 18 -- The Cambodian Ministry of Defense on Tuesday afternoon sent four helicopters and two ships to search on its sea for the missing Malaysian Airlines flight MH370.

The plane vanished over south Vietnam on March 8. "At the behest of the head of the government, the Navy and the Air Forces have dispatched four Z-9 utility helicopters and two P46 ships as well as some armed forces to search at islands and maritime space near the Vietnamese border," said a ministry's statement.

The statement said the ministry has also ordered all armed forces stationed at all islands in Cambodian sea to help search for any suspicious objects relevant to the missing jet. "The Ministry of Defense vows to actively join with other countries to search for the missing jetliner and is ready to help facilitate and support the China-Malaysia search and rescue team if they want to come to Cambodia for further search or investigation," the statement said.

The ministry also extended deep sympathy and condolences to the family members of the passengers aboard the missing plane.

The airliner, with 239 people including 154 Chinese nationals on board, went missing on its way from Malaysia's Kuala Lumpur to China's Beijing on March 8, the airlines said, adding that it lost communication and radar signal two hours into the flight over south Vietnam at 1:20 a.m.that day.

Malaysia on Saturday decided to shift the search to one of the two possible corridors -- a northern one from the border of Kazakhstan and Turkmenistan to northern Thailand, and a southern one stretching from Indonesia to the southern Indian Ocean.

Malaysia's acting Transport Minister Hishammuddin Hussein said that the number of countries involved in the search and rescue operation had risen to 26 on Monday.