Riyadh: At least three people were killed and more than 50 wounded when three powerful blasts rocked the Saudi capital, including one at a residential compound for mainly US nationals and another targeting an American consultancy.

A state department official said the United States believes three car bombs were detonated in front of three Riyadh compounds late on May 12 night housing American and other Western nationals.

The Saudi interior ministry confirmed the three explosions without immediately detailing the targets of the blasts, which occurred on the eve of a visit to the kingdom by US Secretary of State Colin Powell who is now in Jordan as part of a Middle East tour.

The explosions also came days after Riyadh announced it had uncovered a cell of the al-Qaida terror network of Saudi-born Osama bin Laden.

Residents said at least three people, including a Western national, were killed in one of the explosions.

The three men -- the Westerner whose nationality was not immediately known, a Saudi and a Lebanese - - died when a blast hit the Al-Hamra residential compound in Eastern Riyadh that is home mainly to Americans and other Westerners.

"Many of the wounded were in critical condition when they were transferred to hospital," one resident told reporters.

Two villas in the compound, on the road to the city's airport, were wrecked and a restaurant and leisure centre burned in the explosion which residents said had been triggered by a car bomb.

Agencies