The escalation in the Taliban-led insurgency meant the nation "faces the worst crisis since the ousting of the Taliban in 2001," they said in a joint statement to the UN team.
The 10-nation Security Council delegation is visiting Afghanistan on the fifth anniversary of the fall of the extremist Taliban regime to assess the UN's efforts to defeat extremism and establish democracy.
This year has been the bloodiest since the Taliban launched their insurgency, with around 3,700 people killed -- most of them rebels.
Many aid agencies had scaled down their work due to the insecurity, the Agency Co-ordinating Body for Afghan Relief (ACBAR) -- an nongovernment organisation umbrella body -- told the delegation in a briefing released to the media.
Some had closed projects or stopped their staff travelling in high risk areas. Others would not send expatriate staff to certain areas because of the threat.
"All aid agencies note that insecurity has greatly impacted the quality of their projects and that in areas where programmes do continue, insecurity undermines effectiveness by increasing support costs and restricting abilities to implement and monitoring properly."
"If this situation persists, then communities living in more remote areas will suffer significantly," the briefing said.
Part of the problem was that major roads were "extremely dangerous" for travellers because insurgents inspected public transport for Afghan government, UN and NGO personnel who were then accused of spying for foreigners and sometimes executed.
Around 24 Afghan NGO workers have been killed in unrest this year.
In an example of the problem, there were more than 200 attacks on education establishments and teachers from January 2005 to June 2006, most of them this year, it said.
In addition, 200,000 students were denied access to schooling due to conflict, the report said citing Human Rights Watch figures.
The report said there was an urgent need for Afghan authorities and the NATO-led force to "put all their efforts into the security sector".
However, "We remain deeply concerned by NATO's involvement in humanitarian affairs which is beyond the technical expertise of military and associated actors."

Copyright AFP (Agence France-Presse), 2006