One of China's largest tour operators has suspended cooperation with Malaysia Airlines and said it will cancel existing flight arrangements with the carrier.

"Considering the fact that a succession of accidents have involved Malaysia Airlines recently, and that Chinese tourists have concerns over the carrier's safety record, we must fulfill our responsibility of ensuring the security of our fellow citizens," Beijing-based China Youth Travel Service said in a statement on Wednesday.

New bookings will be suspended and existing itineraries that include Malaysia Airlines will be changed to other carriers, it said.

The agency also promised full refunds to consumers who want to cancel trips that would have used the Malaysian carrier.

Another large travel agency, China International Travel Service Head Office, has seen a sharp decline in consumers signing up for tours to Malaysia, according to its publicity officer, Meng Qingfu.

Malaysia Airlines Flight MH370, which shuttled large numbers of Chinese tourists between Kuala Lumpur and Beijing, has been missing for nearly three weeks.

Malaysian Prime Minister Najib Razak announced on Monday that the aircraft crashed into the southern Indian Ocean and that there were no survivors. But an international search operation continues to race to find the missing Boeing 777.

Adding to the jitters about travel to Malaysia, another aircraft, Malaysia Airlines Flight MH066 from Kuala Lumpur to Incheon, South Korea, was diverted to Hong Kong International Airport early on Monday because of a mechanical problem involving an inoperative electrical generator.