KABUL: A rocket apparently fired by fighters from the radical Islamic State movement has hit a mosque in eastern Afghanistan, killing six worshippers and wounding four others, a local official said on Saturday.

The attack in Achin, southeast of Jalalabad in Nangarhar province, occurred during evening prayers on Friday, district governor Haji Ghalibhe said.

It was not clear if it was aimed at the mosque or went astray after being fired at security forces based nearby.

Islamic State has been building up its presence in Afghanistan while battling both government forces and the Islamist Taliban movement. Nangarhar, on the border with Pakistan, has become one of its main strongholds.

Hazrat Hussain Mashriqiwal, a spokesman for the Nangarhar police chief, said security forces had detained two suspects, one of whom was a foreigner.

Islamic State's rise has caused alarm outside Afghanistan, with Russia saying it was concerned about the threat to its central Asian neighbours and U.S. commanders citing the movement as a reason to delay plans to pull out troops next year.