"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.
