International donors meeting in Japan on Sunday pledged $16 billion US in badly needed development aid for Afghanistan over the next four years when most foreign troops will leave.

The major donors' conference, attended by about 70 countries and organizations, is aimed at setting aid levels for the crucial period through and beyond 2014, when most NATO-led foreign combat troops will leave and the war torn country will assume responsibility for most of its own security.

Japan's foreign minister and U.S. officials said the donors had made $16 billion available through 2015, which would be in line with the nearly $4 billion per year that the Japanese co-hosts had said they were hoping to achieve during the one-day conference in Tokyo.

Japan, the second largest donor, said it would provide up to $2 billion through 2016.

The U.S. portion was expected to be in the decade-long annual range of $1 billion to this year's $2.3 billion.

Officials declined to outline the future annual U.S. allotments going forward, but the Obama administration has requested a similarly high figure for next year as it draws down American troops and hands over greater authority to Afghan forces.

The total amount of international civilian support of $4 billion a year represents a slight trailing off from the current annual level of around $5 billion.

That number is somewhat inflated by U.S. efforts to give a short-term boost to civilian reconstruction projects in Afghanistan, mirroring President Barack Obama's decision in 2009 to ramp up military manpower in the hopes of routing the Taliban insurgency.

Canada will contribute an extra $227 million in development aid to Afghanistan between 2014 and 2017. The money is in addition to the initial commitment of $300 million that Canada promised between 2011 and 2014.

The aid is intended nevertheless to provide a stabilizing factor as Afghanistan makes the transition to greater independence from international involvement.

But it will come with conditions.

The donors were expected to set up review and monitoring measures to assure the aid is used for development and not wasted by corruption or mismanagement, which has been a major hurdle in putting aid projects into practice.

The pledges were expected to establish a road map of accountability to ensure that Afghanistan does more to improve governance and finance management, and to safeguard the democratic process, rule of law and human rights - especially those of women.

Before the conference, Japanese officials said they were seeking a mechanism to regularly review how the aid money is being spent, and guarantees from Kabul that aid would not be squandered.

Afghanistan has received nearly $60 billion in civilian aid since 2002.

The World Bank says foreign aid makes up nearly the equivalent of the country's gross domestic product.

Foreign aid in the decade since the U.S. invasion in 2001 led to better education and health care, with nearly eight million children, including three million girls, enrolled in schools.

That compares with one million children more than a decade ago, when girls were banned from school under the Taliban.

Improved health facilities have halved child mortality and expanded basic health services to nearly 60 per cent of Afghanistan population of more than 25 million, compared with less than 10 per cent in 2001.

But the flow of aid is expected to sharply diminish after international troops withdraw, despite the ongoing threat the country faces from the Taliban and other Islamic militants.