'I was told there were three or four, but no one was injured. Things are very tense in Xinjiang. There is an armed police presence in many places. There's a state of high alert.' Officials in Khotan confirmed there had been explosions, but denied they were caused by bombs.

'I don't know exactly what happened,' said one. 'I heard it was just some small detonators, not real bombs.' Another official, from the party's Legal Committee offices, said: 'The detonating device was very small and no one was injured.' Ten days ago, a bomb went off in Korla, on the northern edge of the Taklamakhan desert. Sources said bomb makers set off the device by mistake and killed themselves.

An official in Korla said there had been an explosion but it was not a bomb. 'There was an explosion of cooking gas caused by a careless resident,' she said.

During his five-day visit which ended in mid-July, President Jiang called for joint efforts to continue the crackdown on the separatist movement, saying it would be a long-term struggle.

His visit followed a summit with Central Asian leaders in Kazakhstan at which they pledged to fight against terrorism and religious fundamentalism.

The authorities rounded up thousands, some say tens of thousands, of Uygur suspects after rioting in Yining city left hundreds dead or injured in February last year and a series of home-made bombs exploded in the capital, Urumqi, claiming at least nine lives.

Uygur terrorists have also murdered Muslim clerics and Uygur officials appointed by the Chinese authorities.

In April this year, police and independence fighters fought a gun battle in which at least three died in Yili.