Japan will play host Sunday to a world conference aimed at charting a course to stabilise poor and war-torn Afghanistan in the decade after foreign combat forces leave.

Representatives from dozens of countries will gather in Tokyo where they are expected to pledge cash and support for the post-NATO era in a country that has known little but war for thirty years.

Afghan President Hamid Karzai, who will be in Tokyo along with US Secretary of State Hillary Clinton and United Nations chief Ban Ki-moon, has called for $4 billion a year in civilian aid.

Without a functioning economy, Kabul covers only a third of the $6 billion it spends each year, not counting security costs, and has for a long time been heavily dependent on aid.

Those inside and outside the country fear that once the US and its allies no longer have to worry about their soldiers dying in Afghanistan after the 2014 pullout, the country could be left to drift into the hands of drug lords and extremists.

Figures from more than 80 nations and international organisations gathering in the Japanese capital are expected to adopt the "Tokyo Declaration", pledging support and cash for Kabul.

As part of the so-called "Transformation Decade" from 2015, participants will issue a framework document stressing the principle of "mutual accountability", offering aid on the condition that Kabul clamps down on endemic corruption.

According to the World Bank, spending on defence and development by foreign donors accounted for more than 95 percent of GDP in 2010-11.

In May an Afghanistan security conference in Chicago involving the countries of the NATO-led coalition adopted a plan to provide $4.1 billion in annual security aid in coming years.

The focus in Tokyo will be on development.

In an interview with the Asahi Shimbun newspaper published Friday, conference co-chairman Japanese Foreign Minister Koichiro Gemba said he was hoping it would result in pledges worth at least $3.0 billion a year.

But he warned the money would come with strings.

"(Kabul) must improve its governance capacity, including eradicating corruption," he said, adding a mechanism to review progress in these areas every two years had to be developed.

On Saturday Gemba said donors will stump up more than $16 billion for four years to 2015, adding Japan would provide up to $3 billion over five years, in addition to $1 billion for Afghanistan's neighbours.

"This scale of pledge will satisfy the fiscal gap that the World Bank and the Afghan government have said would be needed for the development of the country," Gemba said.

His announcement came hours after Clinton said the United States had designated Afghanistan a major non-NATO ally, giving it special privileges.

Clinton announced the move, which provides a long-term framework for security and defence cooperation, during a brief visit to Kabul where she had a breakfast meeting with Karzai.

"We see this as a powerful symbol of our commitment to Afghanistan's future," she said at a news conference after talks in Kabul with Karzai.

Tens of billions of dollars have poured into Afghanistan since the US-led invasion that toppled the Taliban in late 2001, but graft is rife from local police to high officials, and patience among donor countries is wearing thin.

Ministers from Britain, France, Germany and Australia, as well as India, Pakistan and Iran, will be present in Tokyo on Sunday, alongside envoys from countries including Russia, Saudi Arabia, Qatar, China and South Korea.

The conference is scheduled to begin at 0000 GMT.