A British oil company executive is among those killed by gunmen in Saudi Arabia, the Foreign Office confirms.
Mr Hamilton was driving to work when he was shot
Michael Hamilton was shot in his car as he drove to work on Saturday, by militants who then attacked a compound in the city of Khobar.
Believed to be in his 50s, Mr Hamilton was a senior executive for Apicorp, the Arab Petroleum Investment Corporation.
Foreign Secretary Jack Straw has condemned the attack in which 22 people are thought to have been killed.
Responsibility has been claimed by a group with apparent links to al-Qaeda.
Prime Minister Tony Blair, speaking on BBC's Breakfast With Frost, said the attack was "yet another reminder about the terrorist threat that we face".
Mr Hamilton, originally from Kilmarnock in Scotland, is believed to have been killed in front of his work colleagues as he drove to work at around 0730 local time on Saturday.
A spokesman for Apicorp said the firm was one of two oil companies which came under armed attack, resulting in the death of three people.
One was believed to be Mr Hamilton while the other two were Saudi security guards, said the spokesman.
The incident escalated when the militants fled to the nearby Oasis residential compound, taking up to 50 people hostage.
Dozens of foreign hostages were freed when Saudi commandos stormed the compound.
Reports said some of the hostages had been killed, either by militants or during the rescue operation.
On Sunday morning, a Foreign Office spokesman confirmed Mr Hamilton had been among the casualties.
It is understood his wife is being cared for by the head of the British Trade Office in Al Khobar.
British ambassador Sherard Cowper-Coles is currently in the troubled city carrying out investigations into the British man's death.
The Foreign Office updated its travel advice, advising against all but essential travel to Saudi. Visitors were warned to "take great care".
A spokesman said it feared more terrorist attacks would be carried out imminently in the Arab country.
On its website it said: "We continue to believe that terrorists remain determined to carry out further attacks in Saudi Arabia, and that these may be
in the final stages of preparation.
"The threat includes, but is not limited to, residential compounds and diplomatic and other official premises."
Mr Straw said the UK would stand by Saudi Arabia in its fight against terrorism.
He said: "I am appalled by the attacks in Al Khobar, Saudi Arabia, and strongly condemn these acts of terrorism.
"I want to extend my condolences to all the families of all the victims of these terrible attacks."
He said British officials in Khobar were in close touch with the Saudi authorities and the British community.
The US embassy has confirmed that an American is among the dead. A 10-year-old Egyptian boy was also killed.
A statement purporting to come from an al-Qaeda-linked group has claimed responsibility for the attack.
The message from the al-Quds Brigade, which said Americans would not be allowed to steal Saudi Arabia's riches, was carried on an Islamic website.