A man in a wheelchair detonated a home-made explosive in Beijing airport.

He injured himself and sent smoke billowing through the exit area of the international arrivals section of Terminal 3.

Individual Chinese unable to win redress for grievances have in the past resorted to extreme measures, including bombings.

Incidents like this are rare amid the tight security of airports, and the motive in this case is not yet known.

There were no other injuries and operations were normal after the blast.

State broadcaster China Central Television said the explosion took place just meters (feet) outside the door from which arriving international passengers depart after picking up their luggage.

It was not clear why the man was at the airport.

An airport spokeswoman declined to speculate about the man's motive, saying airport police were still investigating.

A Reuters witness said things had returned to normal about 90 minutes after the explosion and there were no signs of extra security.

Explosives are relatively easy to obtain in China, home to the world's largest mining and fireworks industries.