An Afghan parliamentary candidate and at least 16 other people have been injured in a mosque bombing in the eastern province of Khost.

Mawlvi Saydullah, the candidate, was delivering a speech during Friday prayers when a bomb exploded inside the mosque.

He and his bodyguard were both wounded by the explosion.

"[Saydullah] was the target," said Mubariz Zadran, a spokesman for the provincial governor.

Nobody has yet claimed responsibility for the bombing, but General Nawab Khan, an Afghan army official in Khost, blamed it on "enemies of Afghanistan".

Afghanistan's parliamentary elections are scheduled for September 18, and security is a major concern.

Last year's presidential elections were marred by dozens of attacks on voters and polling places.

Khost is one of Afghanistan's least secure provinces. Anti-government groups staged 364 attacks there between April and June, up from 240 during the same period in 2009, according to a recent report from the Afghanistan NGO Security Office.

The Haqqani network, one of Afghanistan's three main insurgent groups, is particularly active in Khost, which shares a border with Pakistan.

Taliban arrests

Meanwhile, the Nato-led International Security Assistance Force (Isaf) said it detained several "Taliban figures" in overnight operations, including the group's former spokesman.

Abdul Hay Motmaen, a spokesman for the Taliban when it ruled Afghanistan, was arrested in Ghazni province on Thursday night, Isaf said in a statement.

Two other suspected mid-level insurgents were arrested in Kandahar province earlier this week.