A suicide bomber has detonated an explosives-rigged vehicle at a security forces position north of Baghdad, killing 15 people.

The attack took place south of the sensitive shrine city of Samarra in Salaheddin province.

Samarra is home to the revered Shia Al-Askari shrine, which was bombed in February 2006, sparking a bloody Sunni-Shia sectarian war.

The position was occupied by a mix of Iraqi soldiers and civilians.

Both groups have volunteered to fight a major jihadist-led militant offensive that has overrun chunks of five provinces.

Security forces folded under the weight of the initial onslaught, in some cases shedding uniforms and abandoning vehicles to flee.

It prompted the government to announce it would arm and equip people who volunteered.

While government forces have since performed better, they are still struggling to carry out effective offensive operations against the militants.