Image copyright EPA Image caption About 50 people were reportedly injured in the blast at stadium in Lashkar Gah on Friday night

A suspected suicide bomber has killed at least 13 people and injured dozens more in a car bomb attack on a sports stadium in the Afghan province of Helmand.

The blast happened at a wrestling match at the Ghazi Muhammad Ayub Khan stadium in the region's capital Lashkar Gah.

The car was reportedly driven into a crowd outside the stadium.

A police spokesman told AFP that the blast happened by the venue's entrance gate after the match had ended.

Photographs from the scene showed badly damaged cars and thick plumes of smoke rising.

Image copyright Aziz Ahmad Shafee Image caption Officials say the explosion happened as spectators were leaving the stadium

"The bomber wanted to go inside the stadium but he was identified by the police and he detonated himself," Omar Zwak, spokesman for the Helmand provincial governor, told AFP.

Conflicting reports in local media suggest the death toll may be higher than so far confirmed.

The Italian NGO Emergency, which provides medical treatment, said on Twitter it had received at least four of those killed.

Afghanistan has seen a surge in attacks in recent months targeting state security forces and civilians.

The annual spring offensive by Taliban militants is expected to begin in the coming weeks.

On Wednesday a suicide car bomb attack killed 31 people at Nowruz New Year celebrations in Kabul.

The Islamic State (IS) group claimed that bombing, but no-one has so far said they were behind Friday's stadium blast.

Large areas of Helmand province are under Taliban control, but government forces and US airstrikes have prevented Lashkar Gah from falling to the group.

In January, a BBC study found that Taliban fighters were now openly active in 70% of the country.

Last month Afghan President Ashraf Ghani offered them peace talks "without preconditions" - but so far there has been little sign of them taking up the offer.

"The enemies of Afghanistan cannot prevent the celebration of traditional, religious and cultural events in the country," Mr Ghani said on Friday after the suicide attack, local media report.