The world’s newest insurgency claimed its latest victims yesterday and, to judge by what local people said, they never knew what had hit them. The casualties were security guards, little more than members of a neighbourhood watch, manning a small checkpoint near the oasis city of Kashgar: a simple barrier across the road, a desk with a log of the passing traffic, and a tent where their bodies were found in the early morning.

“There were four of them in the tent,” said a man at a similar checkpoint, a few miles away. “Someone came in during the small hours – they were killed while they slept.” Knives were the weapons used; one man of the four survived and lies in hospital in a critical condition. No one knows who the attackers were, how many there were, or where they are now.

The three deaths yesterday brought to thirty-six the number of people killed by suspected Islamic separatists from the western Chinese region of Xinjiang since last month – thirty-one of them have occurred in just eight days.

Such events are so unprecedented in China that it is difficult to be sure who is behind them. It looks ominously like the beginnings of a situation that any government dreads – a concerted campaign of terror, in this instance carried out by Muslim separatists of the Uighur race, and targeted at Chinese immigrants and those regarded as their collaborators.

Accounts of the attack were still contradictory last night. The state Xinhua news agency reported that it took place at 9am when a group of men jumped out of a passing car. The full story may not be known until, or unless, the survivor of the attack recovers. “He has pulled away from danger,” a policeman in Yamanya told the Associated Press. “We are now waiting for him to wake up and speak so we can find out more details about what happened.”

It was impossible to reach the place where yesterday’s attack happened, near the town of Yamanya, 35km (20 miles) from Kashgar. Police demanded identification at a series of checkpoints, and reluctantly allowed our car to pass. Finally, close to the village of Jiashi, we were intercepted by a patrol car and ordered back on to the main road to the city of Kashgar. “This area is closed to foreigners,” said one policeman. “The criminals have escaped and we don’t know where they are or who they are.”

The attacks began last month with bus bombs that killed two people in the southwest city of Kunming, and they gathered momentum as the Beijing Olympics appraoched. On Monday last week, two Uighur men drove a truck into a unit of policemen in Kashgar, threw bombs and set about them with knives, killing sixteen.

In Kuqa, another oasis city on the far side of the Taklimakan desert, 17 separate attacks occurred early on Sunday, killing twelve people, including ten attackers, two of whom blew themselves up. The authorities have not so far identified any individual group as responsible – and two videos on the internet claiming responsibility are dubious.

There are no plausible candidates other than the shadowy groups who, over the years, have called for independence for the region that they refer to as East Turkestan, either in the name of Uighur nationalism or Islamic fundamentalism, or both. “I think we are seeing an upturn in Uighur militancy,” said Nicholas Bequelin, a researcher based in Hong Kong for Human Rights Watch, and an expert on Xinjiang. “[The attacks yesterday were] unprecedented in terms of organisation. It is an incredible act of defiance during the Olympics, a moment most precious to the Government when they most want to avoid any kind of trouble or separatist violence.” Mr Bequelin said that the use of two female attackers, one of whom committed suicide, appeared to be a first in China.

Even on the main road running north of the Taklimakan desert, there were repeated checkpoints where the identities of passengers were checked and vehicles were searched by police carrying sub-machineguns. Local militia men in camouflage uniforms were to be seen carrying medieval-style pikes in a patrol close to the main road.