An Islamic website has published a statement claiming to be from al-Qaeda militants in Saudi Arabia threatening to attack Western airlines and sites frequented by Westerners in the Arabian peninsula.
The statement follows yesterday's attack in the Saudi capital, in which Simon Cumbers, an Irish cameraman working for the BBC, died after being shot by suspected Islamic extremists.
Mr Cumbers, who was 36, was from Navan in Co Meath.
The BBC is sending a team to Riyadh to investigate the circumstances of his death.
The BBC's security correspondent, Frank Gardner, was also seriously injured in the attack.
The Minister for Foreign Affairs, Brian Cowen, has expressed his sincere condolences to Mr Cumber's family.
Mr Cowen said an attack such as this on journalists in the course of their duty was abhorrent and deeply shocking.
It was, Mr Cowen said, in many ways an attack on a vital pillar of democracy.
Earlier today, reacting to the attack, the British Prime Minister, Tony Blair, said the world needs to remain vigilant against the threat of terrorism.
Mr Cumbers was a freelance journalist and cameraman who had worked throughout the world, covering stories including the signing of the Good Friday Agreement, the Omagh bombing and the war in Iraq.
Mr Cumbers started his career as a teenager in pirate radio in Dublin before going on to work for ITN in the North. He owned his own film production company in London.
Separately, security forces in Saudi Arabia are still searching for the gunmen who carried out the attack.
Journalists should not leave: Saudi ambassador
The two had been in Saudi Arabia for five days filming a series of reports on the country's growing insecurity following the recent terrorist attacks on oil workers in Khobar, which left many foreign workers dead.
The Saudi ambassador to Britain, Prince Turki al-Faisal, has offered his condolences to the families of both men.
Despite the recent violence against foreign citizens and oil workers, Prince al-Faisal said journalists should feel able to remain in the kingdom.
