KABUL - Taliban insurgents trying to seize a southern Afghan city killed 14 people including 10 policemen in a coordinated attack which started with a car bombing Monday, officials said.

The assault was the militants' latest attempt to capture the besieged Helmand provincial capital of Lashkar Gah after they gradually expanded their foothold across the opium-rich province.

"The enemy attacked to breach the security belt in Lashkar Gah this morning, but the attack was repelled by Afghan security forces," said interior ministry spokesman Sediq Sediqqi.

He said seven militants were killed but did not give a figure for other deaths.

An official source told AFP on condition of anonymity that, apart from the insurgents, 14 people including 10 police were killed and 10 wounded.

The early-morning attack began with a car bombing in an attempt to break through the security belt, a security source and local residents told AFP. The blast killed 10 police officers, with at least 14 police and civilians wounded, said the official

"They seized a check post for an hour before they were pushed back by Afghan special forces," said a local elder, Maulawi Hanafi.

A hospital run by the Italian charity Emergency said it had received 30 casualties from the blast, including civilians and security forces.

Hospital officials expressed concern over worsening conditions in Lashkar Gah, with reports of increased Taliban attacks on the outskirts, and rockets landing inside the city.

The Taliban have waged an insurgency against the western-backed Kabul government since being toppled from power by a US-led invasion in 2001. They have intensified attacks across the war-torn country in recent months, pressuring Afghan forces stretched on multiple fronts.

In addition to Lashkar Gah, the militants have attempted to overrun other provincial capitals, from Kunduz and Baghlan in the north to Farah in the west in recent days, but Afghan forces have managed to repel the attacks.

Afghanistan on Friday marked the 15th anniversary of the invasion. The campaign has become Washington's longest military intervention since Vietnam.