China has blamed a little-known Islamist group operating across Asia for a terrorist attack in Beijing's Tiananmen Square.

China's top security official said the suicide car crash that killed five people in the symbolic square in the heart of the capital was organised by the East Turkestan Islamic Movement (ETIM).

"The terrorist attack in Beijing was organised and premeditated," said Meng Jianzhu, the secretary of the Central Politics and Law Commission of the Chinese Communist Party.

"The instigator behind the scenes is the terrorist group the East Turkestan Islamic Movement that operates in central and west Asia."

At least 38 people were injured after a Jeep ploughed into a crowd of tourists and burst into flames in the vast square near the Forbidden City, killing two tourists and three people in the car. No group has claimed responsibility for the crash so far.

Police identified the perpetrators - a man, his wife and his mother - as members of the Turkic Muslim Uighur minority. Another five Uighurs were arrested on suspicion of conspiring in the strike.

The nine million-strong Uighurs live predominantly in the northwestern region of Xinjiang, where they are the largest ethnic group, and complain they are discriminated against by Chinese ethnic Han migrants who have flooded into the region in recent decades.

Xinjiang witnesses periodic outbreaks of anti-government and anti-Chinese violence that authorities have often blamed on the ETIM.

Uighurs have close cultural and linguistic ties to Turkic peoples of Central Asia. Beijing has accused Uighur separatists of plotting to establish an independent state called East Turkestan.

"The ETIM has incited, organised and committed terrorist attacks of various forms in China over the years and spread the ideas of violence and terrorism," Foreign Ministry spokeswoman Hua Chunying said.

"It has been the most direct and real threat to our security, and has damaged the security of other countries and regions."

The ETIM is designated as a terrorist organisation by the UN. However the US recently removed the group from its terrorist watch list amid doubts that it existed in any organised manner.

The Tiananmen attack was the first act of alleged Uighur unrest that spilled from the Central Asian border into the capital.

Activists expressed doubts the ETIM has the capacity of launching strikes against highly sensitive targets such as Tiananmen Square.

Hong Kong-based Human Rights Watch senior researcher Nicholas Bequelin described Meng's claim as "doubtful at best."

"Such violence is not evidence that the ETIM exists or that this was the work of ETIM," said Bequelin.

Being the symbolic centre of the Chinese state, Tiananmen has always been the site of pro-democracy protests, including the infamous June 4, 1989 student-led protest that was brutally quelled by security forces.

The square has since been kept under tight security.