An Interior Ministry source said four other security personnel were injured in the clashes in the city's eastern Al-Fayha district.

Several other "militants" are reported to have fled the scene.

The Saudi authorities have clamped down heavily on Islamic militants since attacks on Western diplomatic compounds in Riyadh in May 2003.

An Interior Ministry statement carried by official SPA news agency said a gunfight broke out after police stopped a suspicious car with two passengers.

The men shot at the police and then took off, coming to a stop in front of a safe house where more militants started to fire at security forces.

One of the suspects fired a rocket-propelled grenade towards police, the statement said.

The security forces have now cordoned off the area in an attempt to trap the suspected militants who escaped.

'Most wanted'

This is the second clash between security forces and suspected militants in two weeks.

One militant was killed and a companion was wounded during a shootout in Riyadh last Monday.

In December, the government published the names and pictures of 26 men it suspected of involvement in terror attacks within the country.

So far, three on the list have been killed and one surrendered.