Taliban seize key battleground in south Afghanistan

One of Afghanistan's most deadly battlefields has been captured by Taliban insurgents, after militants overran the district on Thursday morning after a year-long offensive.

Taliban fighters captured Sangin in southern Aghanistan's troubled Helmand province in the early hours, the district's police chief Mohammad Rasoul told AP, after militants stormed the centre of the town.

Sangin was the bloodiest district for British and US troops, who fought constant battles with militants there following the 2001 overthrow of Taliban government.

The fall of Sangin comes after a year-long offensive by the Taliban and coincides with a spike in violence in other parts of the troubled country.

In the north, an insider attack at a security checkpoint left nine officers dead, when an undercover militant turned his gun on his sleeping comrades in Kunduz province.

Taliban spokesman Zabiullah Mujahed claimed responsibility for the attack.

The increased insecurity in the country has led Afghanistan's government to call for more US troops to boost defences against the Taliban after the militants' launched their annual Spring Offensive.

Foreign Minister Salahuddin Rabbani backed calls by US generals to ramp up US military support for the Afghan government following a bloody month for security forces in the country leaving scores dead.

Agencies contributed to this story.