Correspondent Ben Brown: "Things went tragically wrong"

Three Britons and one Australian died during a rescue operation in the mountains of the southern province of Abyan.

Eyewitnesses at the hotel where the survivors were taken said they looked shocked. Our correspondent says one injured woman had lost her husband and another traveller had lost his wife.

Two wounded survivors - a Briton and an American - were admitted to a hospital intensive care unit, but their condition is not thought to be life-threatening.

Correspondent Rageh Omaar: The Yemeni Government had had enough

The UK's Foreign Secretary, Robin Cook, confirmed the deaths on Tuesday night.

Mr Cook said "others" had been injured in the incident and all next of kin had been informed.

The four dead and two injured were among a party of 16 Western tourists - 12 Britons, two Americans and two Australians - who were travelling with the British-based tour operators Explore Worldwide. They were abducted despite having a police escort.

The 10 who were not injured in the rescue operation have been re-united with tourists who managed to escape Monday's ambush.

Two of the kidnappers are also believed to have been killed by the Yemeni security forces in a shoot-out.

Four others have been arrested and face the death penalty under legislation introduced in the summer in a bid to stamp out kidnapping in the Yemen.

Brian Hanrahan: "A tougher approach to kidnapping"

Sketchy details have begun to emerge from the survivors. They say they were being moved about the mountains and being broken up into smaller groups when the rescue operation began.

It is not yet clear what happened next or who shot first but Yemeni officials say security forces intervened when the kidnappers - believed to be Islamist militants - began killing their captives.

However, our correspondent says a source close to Yemen's President Ali Saleh told him the casualties were the unfortunate result of a planned operation to free the hostages. He says it appears to have been a massive "botch-up".

Travel advice changed

UK Foreign Office Minister Baroness Symons said: "This has been an agonising day for the families and our hearts go out to them and particularly those who have suffered bereavement. It's been a terrible day.

Gulf Correspondent Frank Gardner: "State of shock"

"I'm afraid that as from today we have had to issue advice that non-essential travel to the Yemen is not advised at all."

About 100 foreigners in have been kidnapped in Yemen in the past six years but this is the time any hostages have been killed.