Explosion rocks Shanghai's Pudong airport

A man hurled a bottle containing home-made explosives inside the main international airport in China's commercial hub of Shanghai on Sunday, injuring four people before attempting to kill himself, authorities said.

The unidentified man removed a beer bottle or bottles with explosive materials from a backpack before throwing one near a check-in counter in Terminal Two at Pudong International Airport, the Shanghai government said in a statement.

He then took out a knife and slashed at his neck, it said, adding the man is now in critical condition in hospital.

His motive was not disclosed. There have been several cases in China of disgruntled individuals setting off explosions or starting fires in revenge for perceived wrongs.

Four passengers were injured in the incident, said the statement on the Shanghai government's official microblog.

The official Xinhua news agency said they included a man from the Philippines, as well as a 67-year-old man and a 64-year-old woman - both described as Chinese. The nationality of the fourth victim was unclear.

The four were slightly injured by glass shards and are being treated in hospital, it added.

A few flights were affected because the incident disrupted the check-in area but the airport later returned to normal operation, Xinhua said.

Online video clips showed dense grey smoke rising to the ceiling of the cavernous terminal, and paramilitary security forces rushing into the building immediately after the incident.

Photos posted online by those claiming to be witnesses showed police keeping people back from the scene and abandoned luggage littering the floor.

The incident came as people returned home after a public holiday and just days before Thursday's opening of a Disney theme park in Shanghai.

In a similar incident, a wheelchair-bound man from southern China detonated a homemade bomb at Beijing international airport in 2013 as a protest at alleged police brutality.

The man, Ji Zhongxing, was later sentenced to six years in jail.

Last year an unemployed man set off an explosion at a public park in the eastern province of Shandong, killing himself and another person and wounding 24.