By Heba Saleh BBC correspondent in Riyadh

Pictures of the wanted men were shown on television

Saudi Arabia has published the names and pictures of 26 men it suspects of involvement in terror attacks within the country.

The Saudi authorities have also offered rewards for information leading to the men's capture.

The men are all Saudi citizens except for one Yemeni and two Moroccans.

The announcement comes after the US ordered its diplomats in Riyadh not to stray from its heavily-fortified diplomatic quarter.

Pictures of the 26 suspects have been shown on Saudi television and printed on the front pages of most of the country's newspapers.

The authorities have also posted a reward of some $2m to anyone offering information which leads to the prevention of an attack.

There are smaller rewards for information leading to the capture of one or more of the suspected men.

Security increased

Hotlines have also been established for receiving tip-offs from the public.

The suspected men are believed to be linked to the suicide bombing which targeted residential compounds housing foreigners in Riyadh last month and in May.

The two attacks were blamed on al-Qaeda.

Britain now warns that further attacks may be in the offing.

This comes at the same time as the American's tightened restrictions on its diplomats, who were previously allowed to leave their compound during the daytime.

Armoured carriers

Security has now been massively increased around housing compounds and shopping malls frequented by expatriates.

Armoured personnel carriers and national guard forces have been deployed at some compounds.

At other locations, concrete blocks and metal spikes on the road prevent cars from parking or bar access completely.

The Saudi authorities say they have arrested 600 people since the start of the campaign against Islamic militants following the first bombings in May.