RIYADH (Reuters) - Two Saudi Arabian policemen were shot dead from an unidentified car in an eastern district of the capital Riyadh early on Wednesday, the official Saudi Press Agency reported citing an unnamed police spokesman.

Policemen Thamer Amran al-Mutairi and Abdulmohsen Khalaf al-Mutairi were patrolling in their vehicle at 1:30 a.m. when they were shot. Last month two policemen were shot and injured in a similar attack in Riyadh.

The authorities are carrying out an investigation into the shooting, the spokesman said.

No-one has claimed responsibility for the attack. Militant Sunni Muslim groups Islamic State and al Qaeda have called on followers in the country in the past to attack targets including the authorities, non-Muslim residents and members of Saudi Arabia’s Shi’ite minority.

Some Saudi Shi’ites have also carried out gun and petrol bomb attacks on police in Qatif district of Eastern Province in retaliation for what local activists describe as systematic discrimination against members of their sect, which Riyadh denies.