Riyadh (AFP) - Unidentified gunmen shot dead a policeman in the capital of Saudi Arabia on Friday, a police spokesman said.

Gunmen in a car opened fire at a patrol in southern Riyadh, killing one of its members, a spokesman for Riyadh region police said in a statement carried by the SPA state news agency.

It was the latest in a series of attacks on security forces in the kingdom which is part of a US-led coalition against Islamic State group jihadists in Syria.

Two Saudi police officers were wounded in a drive-by shooting in Riyadh in late March, days after the kingdom started to lead an campaign of air strikes targeting Shiite rebels in Yemen.

On March 22 the United States resumed consular services in the Gulf state following a week-long closure over unspecified "heightened security concerns".

Saudi security forces also occasionally come under attack from opponents in the country's Shiite-populated Eastern Province.

Attacks on police are rare in the capital, however.

Meanwhile, the interior ministry said Friday it foiled an attempt to smuggle explosives to the kingdom across the causeway linking its Eastern Province with Bahrain.

Saudi authorities arrested the smugglers and were investigating with their counterparts in Bahrain to find out the motives behind the attempt, the ministry spokesman said in a statement carried by SPA state news agency.