The Shanghai Airlines Boeing 737 was flying from Shanghai to Cambodian capital Phnom Penh with 149 passengers late on Wednesday when an alarm alerted the pilots to a problem with a fuel pump, the official Xinhua news agency said. The aircraft landed safely in Hainan's provincial capital Haikou, the report added.

An investigation is under way. An Air China flight turned back half way from Beijing to Hangzhou on Thursday after police received a threatening call, Xinhua said, citing a company spokesman. It turned out to be a "false alarm", it said without elaborating.