Anonymous gunmen killed three Iranian security guards in an ambush near the Iraqi border, Iran's official media reported on Wednesday.

The victims, two police officers and a sergeant, came under fire while patrolling a border area in Kurdish-dominated Kermanshah province in the late hours of Tuesday, Khabar (News) Network quoted a police spokesman as saying.

The spokesman gave no indication the killings were related to the violence in Iraq, where Islamist militants fighting the government have captured a number of border crossings between Syria and Iraq..

He did rule out any involvement by PJAK, an Iranian offshoot of Kurdistan Workers Party (PKK), a Kurdish rebel group in neighbouring Turkey with a long history of armed struggle for independence.

However, the police governor general of Kermanshah said evidence suggested the attacks were carried out by elements linked to PJAK, according to comments carried by Mehr news agency today.

PJAK randomly strikes Iranian targets from across the border, and earlier this week, Iran's army said its had "decimated" a band of PJAK guerrillas as they tried to sneak into Iran.

Iranian Kurds, who make up about a tenth of the country's 80 million population, have a long history of struggle for autonomy. But their campaign has been overshadowed by pockets of militants within the ethnic group, who draw violent responses from central governments.-Reuters