CHONGQING -- All flights at the Jiangbei International Airport in southwest China's Chongqing Municipality were disrupted for over one hour following a bomb threat, sources with the airport said Friday.

The airport received an anonymous call at around 6:30 p.m. Friday, in which the caller claimed that a plane had a bomb onboard, according to one airport source.

The airport immediately carried out safety inspections on all flights. Inbound flights were forced to return to the airport and outbound flights were delayed, according to the source.

Another source with the airport said the threatened flight was bound for Shanghai.

The airport lifted the emergency alert at 7:50 p.m. and resumed flights.

An investigation is under way.

Also on Friday, another bomb threat caused flight 9C8856 of Spring Airlines, a private carrier in China, to land in Fuzhou, capital of east China's Fujian Province, for a safety check.

The flight was travelling from the south China city of Guangzhou to Shanghai in the east, according to Zhang Wu'an, a spokesman for the company.