China has said it is examining a statement from a separatist group which is threatening to attack the forthcoming Olympic Games.

The group, calling itself the Turkestan Islamic Party, also claimed to have carried out bomb attacks on buses.

The blasts, in the port of Shanghai and the western province of Yunnan, happened over the last three months.

China has previously denied the explosions were the work of militants but has warned of threats to the games.

Earlier this month, officials said they had broken up five terrorist groups in the mainly Muslim Uighur region of Xinjiang region in the north-west.

Critics have said the threats are being exaggerated to justify repressive measures in the region.

The Washington-based IntelCenter, which monitors terrorism communications, said the group had released a video entitled 'Our Blessed Jihad in Yunnan'.

In it, the group's leader, Commander Seyfullah, claimed credit for several attacks and threatened next month's Olympics.

"Despite the Turkestan Islamic Party's repeated warnings to China and international community about stopping the 29th Olympics in Beijing, the Chinese have haughtily ignored our warnings," IntelCenter quoted him as saying.

"The Turkestan Islamic Party volunteers who had gone through special preparations have started urgent actions."