French investigators said Monday it was too soon to consider launching undersea searches for the wreckage of the Malaysia Airlines jet that officials said went down in the Indian Ocean.

France's BEA accident investigation service, which had sent three investigators to Kuala Lumpur, said the "vast area (involved) does not, at present, make it feasible to conduct undersea searches."

"An undersea phase to localise the aeroplane from flight MH370 could be launched only if the operations under way today enable a more limited search area to be defined than the current search areas," the BEA said in a statement.

It said its investigators, who had returned from Kuala Lumpur at the weekend, had discussed possible techniques for undersea searches with Malaysian authorities.

In particular they discussed "their experience... acquired during the search between 2009 and 2011 for the wreckage of Rio-Paris flight AF447," it said.

It took 23 months for BEA investigators to find the wreckage of the Air France flight after it went down in the Atlantic in 2009.

Malaysia on Monday said the MH370, which went missing more than two weeks ago, crashed in the Indian Ocean, but shed no light on the mystery of why it veered from its intended course.