BBC reporter still critically ill

Gardner and Cumbers were filming when they were shot

BBC security correspondent Frank Gardner remains critically ill in hospital after being shot by gunmen in the Saudi capital Riyadh.

Gardner, 42, an expert on al-Qaeda, had hours of surgery after the attack.

Cameraman Simon Cumbers, 36, was killed when they were shot with a machine pistol apparently from a jeep in a southern suburb of the city.

Saudi security forces are hunting the gunmen who struck as they filmed the house of an al-Qaeda militant.

UK Prime Minister Tony Blair, the Saudi ambassador to Britain and colleagues are among those who paid tribute to both men.

Gardner on security fears Profile: Frank Gardner Black year for media

The two journalists travelled to Saudi Arabia last week after attacks in the city of Khobar which killed 22 people.

They were in the al-Suwaydi suburb of Riyadh with a Saudi government minder when the shooting happened.

BBC correspondent Paul Wood reported that the suburb is known as a militant stronghold and home to 15 of the 26 most wanted men in Saudi Arabia, including Abdul Aziz al-Muqrin, suspected leader of al-Qaeda in the kingdom.

Recent statements by Islamic militants have made clear that any Westerner in Saudi Arabia is considered a legitimate target.

Tributes and concern Obituary: Simon Cumbers

The reports Gardner and Cumbers had already filed from Saudi Arabia spoke of a new climate of fear among expatriates.

Security sources said the gunmen had escaped and roadblocks had been set up in an effort to catch them.

Riyadh's police chief said "unknown elements" were responsible for the attack.

The men's minder is believed to have escaped unharmed and is now being questioned, Saudi security sources say.

The Foreign Office has advised against all but essential travel to the country and says it believes further terrorist attacks are planned after the Khobar killings.