"If it's possible to have a conference in Kabul I would prefer that," said Carl Bildt after talks in Brussels on Tuesday with his EU counterparts.
Earlier this month Europe's big three -- Britain, France and Germany -- unveiled proposals for the conference in order to press Afghans to take more responsibility for their own country.
The conference, at which the United Nations and the United States are expected to be represented, will be focused on three areas: security, government and development, according to the British side.
The proposal comes as the international mission grows unpopular in some of the 42 countries that make up the 100,000-strong foreign contingent in Afghanistan, 65,000 from the NATO-led International Security Assistance Force.
The Taliban insurgency has proved to be tenacious, with militants seeking refuge in neighbouring Pakistan, and Western countries have grown frustrated about widespread corruption in President Hamid Karzai's government.
No date has been set yet for the conference, to be held at a ministerial level, but it will take place after a new Afghan government takes office and be co-chaired by the United Nations and the new Kabul leadership.
EU Enlargement Commissioner Olli Rehn backed the idea of the conference taking place in the Afghan capital, saying it would send "a political signal of progress in Afghanisation".
Precisely when a new administration will be in place in Afghanistan remains unclear with no result yet from a controversial presidential election last month.
The EU ministers met as the electoral complaints body in Kabul announced that ballots at 10 percent of Afghanistan's polling stations would be recounted due to indications of fraud.
The European ministers stressed that the most important thing was that a credible government emerge at the end of the process.