The UN Security Council has extended the mandate of the International Security Assistance Force (Isaf) in Afghanistan.

The extension of the force's mandate by another six months was unanimously approved.

The US-sponsored resolution extends the authorisation for the nearly 4,500-member force after its initial six-month mandate ends on 20 June.

Command for Isaf is also expected to transfer from Britain to Turkey at about the same date.

"The situation in Afghanistan still constitutes a threat to international peace and security, [but] the responsibility for providing security and law and order throughout the country resides with the Afghans themselves," the resolution said.

Loya Jirga concerns

United Nations officials had been concerned about security in Afghanistan ahead of a Loya Jirga - a gathering of tribal leaders next month that's due to decide the shape of a new government.

At the debate before the passing of the resolution, a senior UN official, Sir Kieran Prendergast, said that security outside Kabul also needed to be improved if the reconstruction of Afghanistan was to be sustained.

"All [the international community's] political and financial efforts in support of a new Afghanistan would be seriously compromised by a lack of tangible progress in the security environment.

"We cannot expect a sustained reconstruction process to be launched in Afghanistan without real improvements in security outside Kabul and its environs," Sir Kieran said.

No troops outside Kabul

The international troops are stationed in and around Kabul.

UN officials indicated that there was no appetite among Security Council members for the idea of extending the force beyond the Afghan capital.

Nations providing the soldiers for the force appear to be more interested in assisting and training the Afghan army and police force.

Officials concede that this will take time, and is unlikely to play a major role in providing security for some time yet.