Many of the November bombing casualties were Muslims

Police in the Saudi capital Riyadh have arrested a man in connection with a suicide bomb attack on a housing compound last month which killed 18.

The man was seized a week ago at a hideout along with a huge arsenal including missiles and tons of explosives, the government said.

It said it had delayed announcing the arrest in the interests of security.

The US and other embassies in Riyadh recently issued warnings of an impending attack in Saudi Arabia.

"Security forces located the hideout of one element of the terrorist cell that carried out the bombing at the Muhaya compound in Riyadh," the interior ministry said in a statement.

"The search continues for other elements of this cell and others like it."

Since a wave of suicide attacks in Riyadh in May, hundreds of people have been arrested in Saudi Arabia in a campaign against the Islamic militant network al-Qaeda and groups which emulate it, the BBC's Heba Saleh reports from the city.

Cement blocks now surround places frequented by foreigners such as hotels and shopping centres.

Arsenal

The location of the hideout was not given but details of the weapons cache suggest a large storage space.

The cache included assault rifles and 168,000 bullets

The official news agency SPA said the arsenal included 38.4 tons of "RDX explosive materials" and "100 Sam-7 missiles", as well as 200 hand grenades, 80 Kalashnikov assault rifles and an unspecified number of rocket-propelled grenade launchers.

Pamphlets "calling for perpetrating terror acts" were also found, the Saudi interior ministry said.

The detainee's identity was not given, also on grounds of security.

In the 8 November attack, suicide bombers attacked a compound housing many diplomats and their families from the Arab world.

As well as the dead, 120 were wounded, many of them children.

Two of the bombers involved in the attack have been identified by police as Saudi nationals.

Attack warning

The US embassy warned that militants might be planning new attacks on compounds housing Westerners in Riyadh.

It said on Tuesday that at least one compound - Seder Village - had been under "active surveillance by terrorist elements".

Britain and Australia have also issued security warnings to their nationals.

The suicide attacks on Western diplomatic compounds on 12 May left 34 dead, including the nine bombers.