Saudi security forces have killed four armed men in a clash in Awamiya region, the Interior Ministry said.

The troops raided a hideout for fighters in the eastern Awamiya town and killed the four in an exchange of fire on Saturday, the ministry said.

The dead, described by the government as terrorists, were behind the killing of a member of the security forces and wounding of another last Sunday, a ministry spokesman quoted by the Saudi state news agency SPA, said.

Among the dead was the leader of that attack, it said.

Awamiya has been the focal point of unrest among Saudi Shia since protests in early 2011 calling for an end to perceived discrimination against the minority sect and for democratic reforms in the Sunni monarchy.

More than 20 people have been killed in the unrest since then, most of them local people shot in incidents that police have described as exchanges of fire.

Some Shia rights activists say several of those killed were shot dead while peacefully protesting, which the government denies.

Saudi Shia complain it is harder for them to get government jobs than Sunnis, or to build places of worship.

The government denies discrimination and has accused Shia activists involved in attacks on security officers or protests as working on behalf of a foreign power, widely understood to mean Iran.