Eleven flights were affected in total, though the suspect is not alleged to be behind all the threats. The planes were travelling from Beijing, Chongqing, Guangzhou and Shenzhen, the Beijing News reported.

One flight from Guangzhou on Friday had to be diverted to Fuzhou following an anonymous call to the airports after takeoff. Passengers were evacuated and the plane and baggage searched.

In three of the 11 cases the planes had already arrived at their destination.

The threats involved Air China, China Eastern Airlines, China Southern Airlines, Sichuan Airlines and Spring Airlines.

A suspect surnamed Ji was arrested and had confessed, Chinese civil aviation information site Carno.com said. His motive was not known.

Five flights operated by three Chinese airlines had already been hit by bomb threats on Wednesday, the official Xinhua news agency said.

Two similar alerts had occurred in February and two in October, the Beijing News said.

According to Wu Xiaojun, a magistrate in Beijing, these threats are most often impulsive acts by angry men in their twenties or thirties.

Making false bomb threats in punishable by up 15 years in prison in serious cases.