"What is important, and this is our joint view, is to apply pressure in order to find a way to get the Afghans to appreciate that they have to take responsibility step by step," German Chancellor Angela Merkel told a joint press briefing with UK Prime Minister Gordon Brown in Berlin.
The conference, the location of which is yet to be decided, "is to create some momentum and to say that we are now coming to a transitional phase following the second presidential election" in Afghanistan, she said.
With the help of an upcoming review by the new US and NATO commander in Afghanistan, General Stanley McChrystal, it will make clear to countries involved in Afghanistan "what job they have to do and what our common aim is,” Merkel said. "The Afghan government will then know what growing responsibilities are going to be coming their way," she said, "and of course so that the international engagement ... can be reduced. We believe that with the presidential election, the time has come."
"It is right in my view," Brown said, "that eight years since September 11, and after many achievements in Afghanistan ... that we look at how we can get the Afghans themselves more involved in taking responsibility for their own affairs."
The conference, which Merkel said had been "informally agreed upon" with the United States and which would include the United Nations, would be focused on three areas: security, government and development, Brown said.
The proposal comes as the international mission grows increasingly unpopular in many of the 42 countries that make up the 100,000-strong international force in Afghanistan, 65,000 of whom form the NATO-led International Security Assistance Force.
A CNN poll last week showed 57 percent of people in the United States, which provides around two-thirds of the foreign troops, now oppose the war in Afghanistan and 40 percent believe it cannot be won. In France, 64 percent are opposed to the mission, according to a survey last month.
The Taliban insurgency has proved to be tenacious, with militants seeking refuge and destabilising neighbouring Pakistan, and Western countries have grown frustrated about widespread corruption in President Hamid Karzai's government.
The presidential election held on August 20, likely to result in another term for the Western-backed Karzai, has been overshadowed by allegations of widespread fraud and vote-rigging.
Civilian casualties have also made international troops unpopular in Afghanistan.
An air strike on Friday in the north of the country ordered by a German commander after the Taliban hijacked fuel tankers killed scores. On Saturday McChrystal promised a full investigation into the strike in which Karzai's office said 90 people were killed and wounded.
McChrystal submitted on August 31 his much-anticipated classified review of America's strategy there that is widely expected to lead to a request for more troops. It has been forwarded to President Barack Obama and is being evaluated by senior military officials.