By Sanjoy Majumder BBC correspondent in Kabul

Ambassadors from all 15 member-nations spent the past four days holding discussions with the government and aid workers, as well as influential provincial leaders and warlords.

Their visit coincided with the release of the final draft of the country's new constitution.

The head of the UN delegation, German Ambassador Gunther Pleuger, said their discussions identified the issue of security as the core problem confronting Afghanistan.

He said it was obvious that greater security could only be achieved by adopting a comprehensive strategy, including continuing to reform the defence ministry and disarming militias.

Meeting rival warlords

A process is under way to restructure the ministry by offering representation to all ethnic groups, a key grievance of the majority Pashtun community.

But Mr Pleuger added that Afghans had to learn to pledge their loyalties to institutions and not to individuals.

One of the highlights of the visit was the meeting in northern Afghanistan between the ambassadors and two rival warlords, Atta Mohammed and Rashid Dostum.

The team urged the two to end their fighting and thereby strengthen the position of the country's president, Hamid Karzai, ahead of next year's national elections.