Taliban militants in Afghanistan have suspended preliminary peace negotiations with the United States.

The militants blamed the Americans’ “ever-changing position”. One key stumbling block was reported to be US efforts to involve the Afghan authorities.

The group has objected to this, as they regard the Kabul government as illegitimate.

Meanwhile, President Hamid Karzai has called on NATO forces to leave Afghan villages after a US soldier killed 16 civilians.

According to officials, the priority for Afghan government was to avoid civilian casualties at any cost.

President Hamid Karzai told the visiting US Defense Secretary Leon Panetta that Afghan troops should take the lead for nationwide security in 2013.

President Hamid Karzai has called on NATO forces to leave Afghan villages after a US soldier killed 16 civilians

In a statement issued on Thursday, the Taliban said the talks should focus on a political office being established in Qatar and on a prisoner exchange.

They said they were suspending the talks because of “the shaky, erratic and vague standpoint of the Americans”.

US diplomatic sources say the Taliban were told by US negotiators that the Afghan government had to be a part of any negotiations.

The Taliban statement reiterated that the group “considers talking with the Kabul administration as pointless.”

Other conditions reportedly set by the US in the talks include accepting of the Afghan constitution – which the Taliban have rejected – and publicly denouncing al-Qaeda.

The Taliban’s suspension of the talks is a significant setback for efforts to begin peace talks with the insurgents.

It was thought that a deal to exchange five Taliban fighters currently held at Guantanamo Bay for a kidnapped American soldier was only weeks away.