Afghan President Hamid Karzai. — Photo by AP

KABUL: Afghanistan's president has raised another condition for a long-awaited strategic partnership with the United States: The accord must spell out the yearly US commitment to pay billions of dollars for the cash-strapped Afghan security forces.

The Tuesday demand threatens to further delay the key bilateral pact and suggests that Afghan President Hamid Karzai is worried that the US commitment to his country is wavering as the drawdown of foreign forces nears.

The US already pays the vast majority of the budget to train, equip and run the Afghan security forces and expects to do so for years to come to compensate for Afghanistan's moribund economy.

But the yearly Congressional budget process, as well as the American public's weariness with the Afghan conflict, would make it difficult for Washington to commit to a dollar figure years in advance.

The strategic partnership agreement is crucial to the US exit strategy in Afghanistan.

American officials hope it will both map the course for US forces after the majority of combat troops leave in 2014 and give the Afghan people confidence they are not about to be abandoned by their most important international ally.

But the talks have often snagged on what appears to be very different opinions of the two governments about what the goals of the document should be.

US officials involved in the negotiations have said it is not meant to set forth exact rules, but to establish a framework between the two countries to continue to work together for years to come.

The Afghan government seems to want the exact opposite, repeatedly demanding concrete commitments and rules for US forces.

It sees the document as necessary to establishing Afghan sovereignty after years of letting policy be set by the international allies who bankroll the government.

Negotiations were dragging at the beginning of the year as Karzai asked for specific commitments from the US before signing, but the main hurdles of the agreements on the transfer of authority over detainees and the conduct of night raids have been resolved in recent weeks.

Afghan and US officials are pushing to sign the deal before a Nato conference in Chicago in May, and with those two issues resolved, that goal appeared within sight.

Then Karzai said on Tuesday that the US needs to go further than vague pledges to continue to fund the Afghan army and police.

''They are providing us money, there is no doubt about that. But they say they will not mention the amount in the agreement. We say: Give us less, but mention it in the agreement. Give us less, but write it down,'' Karzai said in a speech in the capital marking the anniversary of the birth of a revered Afghan writer.

U.S. officials have said they expect to pay about $4 billion a year to fund Afghan forces. Karzai said he wants a written commitment of at least $2 billion. He said he would rather have a firm commitment to a lower figure than a verbal promise for a higher one.

''You have to mention 'at least' in there,'' Karzai said.

Neither side has said exactly how long this financial commitment is expected to last.

The comments suggest Karzai may be growing increasingly worried that the US will not make good on funding pledges once there are drastically fewer American soldiers risking their lives on Afghan soil.

Many Afghans feel they were abandoned by the U.S. after the Soviets pulled out of Afghanistan in 1989 and worry that the same thing will happen again when American troops depart.

The US has already greatly reduced the money it spends on development programs in Afghanistan and the past year has seen a number of Nato nations trying to speed their exits from the country even as they continue to promise to support the Afghan government.

On Tuesday, Australia became the latest ally to speed up its timetable as Prime Minister Julia Gillard said they expect to pull out troops nearly a year earlier than what had been an expected 2014 departure.

A spokesman for the US Embassy in Kabul declined to comment on Karzai's demand.

US officials have said they expect the document to address economic and development support for Afghanistan but it is unclear if the American negotiators would have the legal authority to make a specific financial commitment.

American administrations request money for specific countries in the foreign aid budget and work with Congress to determine amounts. A guaranteed sum would be highly unusual, especially with the current Democratic administration and a Republican-controlled US House.

At a time when the US is facing budget cuts in domestic programs and a sluggish economy, members of Congress have increasingly questioned the wisdom of spending billions of dollars in both Afghanistan and Iraq.

Attacks by Afghan troops against the American forces who are supposed to be training them has also raised doubts about whether the money is worthwhile.