A man in a wheelchair ignited a home-made explosive device at Beijing's international airport Saturday, state media reported, injuring himself but no others.

The man, identified as Ji Zhongxing from Shandong province, aged 34, was being treated for injuries, the state-run Xinhua news agency said, citing police.

The explosion, which occurred in the airport's Terminal 3, caused momentary panic and confusion at one of the world's busiest airports, although no one else was hurt, Xinhua said.

Stephanie Kleine-Ahlbrandt, a Chinese foreign policy specialist at the International Crisis Group think-tank who was inside the arrivals hall at the time, described on Twitter seeing a "huge explosion followed by panic, smoke and dust".

Pictures she posted online showed a female Chinese police officer waving crowds back as dense white smoke drifted across the terminal.

In a separate tweet she said the blast had created "lots of excitement" and that police had become angry and "shouted crowds back and told everyone to leave".

A Chinese microblogger, under the username Ruhuaerdaye who had come to the airport to pick up his wife, posted: "Right now this place is full of armed police and firefighters", adding he could see "one person lying on the floor covered in white cloth, nearby is a wheelchair toppled over and a suitcase".

Another microblogger at the airport, Chihewanlezaibeijin, posted that someone holding a bomb "shouted for a while but nobody paid attention, until he opened up a white plastic cover over the bomb. Only after the people around him realised something was wrong did the security guards rush over. The security guards only said two words before the bomb went off".

On social media and Chinese websites a photo -- purportedly taken just before the explosion occurred -- showed a man in a peach coloured shirt sitting in a wheelchair with his hands in the air holding a white package.

Some Chinese news and social media sites showed what they said was a blog written by the man police identified as Ji.

In it, Ji says he formerly worked as a motorcycle driver ferrying passengers in the southern Chinese city of Dongguan and was severely beaten by police staff in 2005. The veracity of the purported blog could not immediately be verified.

Xinhua said the blast came at about 6:24 pm (1024 GMT), adding that police were investigating.

According to the preliminary investigation, police said that the Ji set off the device immediately after being obstructed from releasing leaflets, Xinhua said.

There were no immediate details on the content of the leaflets or what, if any, complaints the man may have.

Police and the airport's information office could not immediately be reached for comment while Xinhua reported that Ji's injuries were not thought to be life-threatening.

China Central Television's Twitter-like microblog said no flights were affected by the incident and that the situation had returned to normal.

An AFP photographer at the airport said there was no sign of increased police presence and travellers were arriving normally.

Photos carried on Xinhua's website showed what appeared to be medical and other workers attending to someone on the floor and people running through the terminal amid white-coloured smoke.

Security at Beijing's airport, the sixth busiest in the world with 557,000 take-offs and landings each year, is tight as are many public locations and transport hubs in the country.

The airport, with three terminals, underwent a massive expansion ahead of the 2008 Beijing Olympics.

Violent crime is rare in China had a murder rate of 1.0 per 100,000 people in 2010, according to the United Nations, among the lowest in the world.

Corruption and police harassment, however, are frequent complaints, which have caused some citizens to seek redress through the courts and petitions to government agencies though they are often blocked from doing so.