Martin Dawes in Uganda: "A planned and brutally executed attack"

American tour leader Mark Ross said there had been no rescue attempt by Ugandan troops.

He said those killed were murdered after being forced to march through the rainforest for a day by a gang of Rwandan rebels.

"The ones that I saw had their heads crushed in and deep slashes," Mr Ross said.

Ugandan officials confirmed four Britons, two New Zealanders and two Americans were among the dead.

The bodies, now awaiting identification in Kampala, are covered in machete wounds.

The tourists were killed after about 150 armed rebels attacked their camps in the Bwindi National Park early on Monday. They had travelled to the remote jungle area in the southwest of the country to see a species of rare mountain gorilla.

Anna Borzello explains who has been released

Six other hostages - two Britons, one New Zealander, one Swiss, one Canadian and one American - were freed after being taken captive.

The victims include four women and four men. Five have been named so far

• Americans Rob Haubner, 48, and his 42-year-old wife Susan Miller
• New Zealanders Rhonda Avis, 27, of Auckland, and Michelle Strathern, 26, of Timaru.
• Briton Mark Lindgren, 23, from St Albans.

'Attempt to destabilise Rwanda'

The abduction was blamed on Rwandan Hutu rebels - Interahamwe - based in the neighbouring Democratic Republic of Congo.

Robin Cook: "This latest tragedy highlights the human cost of the ongoing conflict"

Witnesses said the rebels stormed the park headquarters, rounded up the tourists and then disappeared into the forest with their captives.

It was earlier thought that the hostages might have died in a botched rescue attempt by Ugandan security forces tracking through the jungle to find the kidnappers.

Survivor Mark Ross, speaking at the US embassy in Kampala, described how he came across a group of three bodies after his captors left him. One of the women had apparently been raped.

Asked if any of the tourists had seen the killings, he said: ''No, if you saw it you were dead.''

The Rwandan rebels told him the idea of the attack was to destabilise Uganda and let the world know there was a war in the Democratic Republic of Congo.

He did not know why some hostages were killed and others released. But contrary to other reports, he did not think the guerrillas had targeted Americans and Britons.

Britons singled out

However, an American tourist who escaped said British hostages had been tortured by the rebels.

Linda Adams fled after faking an asthma attack as she was marched into the jungle.

She said that at least one British man had been beaten by his captors and that the British people had been ''treated quite badly".

Gun fight

BBC Africa Correspondent Jane Standley explains why the tourists would have gone to Uganda

A UK Foreign Office spokesman said there appeared to have been some kind of a gun fight between the rebels, park rangers and soldiers.

He said five of the bodies were found at the site of the gun battle and three were found nearby.

UK Foreign Secretary Robin Cook said Britain had told Uganda it did not want any intervention that might put lives at risk.

In December, four Western tourists held hostage in Yemen died during a rescue attempt by Yemeni forces.

Earlier releases

Diplomats have been arriving at the national park - also known as the Impenetrable Forest - where the group was taken hostage.

Seven of the tourists rounded up on Monday were released on the same day, including France's Deputy Ambassador to Uganda, Anne Peltier, who negotiated the release of all the French tourists and some Australians.

She said firing had started around the tent where people were sleeping.

Eric Naigambi, Asst Superintendant. Ugandan Police, Kampala

"Suddenly some soldiers came in the tent and they asked for money, for jewellery, for watches."

Twelve tourists escaped the kidnappers by fleeing into the jungle and arrived later in Kampala.

Gruesome reputation

The Hutu rebels - the Interahamwe - fled Rwanda after they took part in the 1994 genocide of more than 500,000 Tutsis.

Fergus Nicoll: "The circumstances surrounding the deaths are yet to be explained"

They have been launching raids into Uganda from bases in eastern Congo to ambush vehicles and kidnap or kill passengers.

Last August they abducted a number of foreign tourists who were on a mountain trek in Congo. All but one are still in captivity.

UK-based travel firm Abercrombie and Kent, which ran a campsite where several of the tourists in the latest incident had been staying, said security was mostly left to local park wardens.

Bwindi National Park, covering 331 sq km, is home to an estimated 300 mountain gorillas - half the entire global population.