Foreign ministers and senior representatives from 85 nations, as well as 16 international organizations, were due Monday to attend a key conference on Afghanistan's future in the former German capital Bonn, DPA reported.
The meeting was expected to focus on the security handover to Afghan forces, as well as international aid and political commitments to the country after 2014, which is the deadline for NATO-led forces to withdraw from the country.
However the meeting will be hampered by the absence of Pakistan, a key force in the region, which pulled out in protest at a NATO attack last month which Islamabad said killed 24 of its security personnel.
US Secretary of State Hillary Rodham Clinton and Afghan president Hamid Karzai - who is to chair the meeting in the former German parliament chamber - were expected among the delegates.
Ahead of the talks, Karzai said Afghanistan would need funds until 2024 at the earliest to build up the police, army and state institutions, in an interview with German Spiegel news magazine.
"Five billion dollars for aid projects would absolutely suffice," Karzai told the magazine.
On Sunday the host of the conference, German Foreign Minister Guido Westerwelle, held bilateral talks with his Iranian counterpart Ali Akbar Salehi and with UN Secretary General Ban Ki-moon.
Pakistan and Iran are the two neighbours with most influence in Afghanistan, and neither favours NATO's peacekeeping operation.