Afghanistan's defence ministry has begun ordering soldiers who have families in Pakistan to move them to Afghanistan in a bid to rid the army of Taliban infiltrators, officials said Saturday.

The new policy was crafted in response to a recent spate of incidents in which Afghan soldiers reportedly with links to militants carried out attacks against NATO troops.

"We have been told to ask our soldiers who have relatives in Pakistan to move them to Afghanistan," Abdul Hamid Hamid, the army corps commander in Kandahar, told AFP, adding that the policy was not yet finalised.

"Sometimes their families are used as hostages by some intelligence agencies to put pressure on them to do what they don't want to," he said.

Most of the soldiers who are recruited in Kandahar have families in Pakistan, he added.

Kandahar is the birthplace of the Taliban whose government was toppled by a US-led invasion in 2001 following the September 11 attacks.

The militants, who are believed to have sanctuaries in Pakistan, have waged an increasing insurgency against the US-backed Afghan government and foreign forces.

"We have put up more strict rules in enlisting the new recruits. Those who have families in Pakistan are checked more seriously," ministry of defence spokesman Daulat Waziri said.

A renegade Afghan soldier who shot dead four French troops in January had visited Peshawar, Pakistan's main northwestern city that borders Taliban and Al-Qaeda strongholds near the Afghan border, before rejoining the army, according to officials.

Six percent of overall NATO deaths in Afghanistan have been attributed to attacks by Afghan security forces, according to a confidential alliance report leaked to the media.

Some 40 attacks were reportedly committed by Afghan forces against NATO troops in the last four years, including 18 last year.

There are about 130,000 NATO troops in Afghanistan, working with more than 300,000 members of the Afghan security forces.