by Nasrat Shoaib Nasrat Shoaib

KANDAHAR, Afghanistan (AFP) –

Taliban fighters on Thursday stormed a police post in southern Afghanistan, killing 10 in the latest in a surge of attacks as the US fine-tuned a new strategy for the war-torn nation.

The brazen early morning attack took place in the Nahri Sarraj district of Helmand province, a Taliban stronghold, the interior ministry said.

"Nine hero policemen were martyred in the cowardly attack by the enemies of Afghanistan," it said, using a phrase that commonly refers to Taliban fighters, who are battling to topple the Western-backed government in Kabul.

Taliban fighters also ambushed police reinforcements from the provincial capital Lashkar Gah led by the deputy provincial police chief Kamaluddin Khan as they were about to arrive at the scene, sparking another battle, Khan said.

"Another policeman was killed and two were wounded in the subsequent one and half hours of fighting," he said.

Taliban fighters left the area after the attack but an operation was under way to hunt down the attackers, he said.

Helmand provincial police chief Assadullah Shairzad said authorities were investigating how Taliban fighters managed to overpower the policemen.

"We are investigating the incident and how it happened," he told AFP.

Deputy provincial police chief Kamaluddin Khan said the insurgents had sustained casualties, but was unable to give any further details.

The small police building lies on a road connecting Nahri Sarraj to the neighbouring district of Nad Ali, and is used to secure both a nearby village and the road, said the deputy police chief.

The Taliban fighters attacks have picked up recently in Afghanistan with the arrival of spring, which has traditionally seen a surge in violence during the country's long years of conflict.

Elsewhere in the south, Taliban fighters ambushed a police convoy carrying a Taliban detainee to the provincial capital of Ghazni, sparking a 30-minute gun battle, Qarabagh district police chief Abdul Ghafor Khan told AFP.

"Seven policemen and two Taliban fighters were wounded, and four Taliban were killed in the battle," Khan, who was also in the convoy, told AFP.

The Taliban fighters abandoned three of their dead before fleeing, he said.

"Four of the wounded policemen are in critical condition," Abdul Hameed, a doctor at Ghazni hospital, told AFP.

The United States is preparing a new strategy for the embattled nation, expected to be unveiled at an international meeting on Afghanistan in the Netherlands next Tuesday, which US foe Iran confirmed it would attend.

It was not immediately clear at what level Tehran would participate at the forum, which US Secretary of State Hillary Clinton will attend.

With Afghanistan mired in war for over seven years and amid dim prospects for peace, the new US administration is mulling a new diplomatic push, but has yet to provide details on its expectations from Tehran.

US President Barack Obama has switched the focus of the "war on terror" from Iraq to Afghanistan and ordered 17,000 more US troops for Afghanistan, where there are already about 75,000 soldiers under US and NATO command.

German Chancellor Angela Merkel said NATO must succeed in Afghanistan in order to stop the country again becoming a base for "terrorists", in a speech to parliament ahead of the alliance's 60th anniversary summit on April 3-4.

Germany has around 3,500 troops in Afghanistan, one of 41 nations forming the 60,000-strong NATO-led International Security Assistance Force. The German parliament voted last year to increase this to 4,500.