A bomb attack killed four girls attending an Afghan wedding, officials said Thursday, blaming the attack on Taliban rebels intending to target government employees at the event.

The children, aged between seven and 12, died when an improvised explosive device (IED) detonated as they collected water from a river during celebrations in the southern province of Helmand.

"The children were at the wedding party and this morning they went to collect water when the IED exploded on a footpath," provincial administration spokesman Omar Zwak told AFP.

"The Taliban may have planted the bomb to hit local government staff who were at the wedding, but it killed innocent children."

Senior police official Mohammad Ismail Hotak confirmed the incident outside the provincial capital Lashkar Gah and gave a similar account.

"Four young girls were killed. The body of one of them has been totally shattered," he said.

Taliban rebels regularly use IEDs to target government officials, and NATO and Afghan soldiers, but civilians and children are also often killed and wounded by the attacks.

According to UN statistics, civilian deaths rose by 24 percent in the first half of 2013 compared to last year.

The United Nations registered 2,499 civilian casualties between January and June, attributing 74 percent to anti-government forces and nine percent to pro-government forces.

Children accounted for 21 per cent of all civilians killed and wounded and casualties caused by IEDs -- the Taliban's weapon of choice-- had risen 41 per cent, it said.

Helmand is a hotbed of the Islamist insurgency that was launched against the US-backed Kabul government after the Taliban were toppled from power in late 2001.