Prime Minister Stephen Harper closed a NATO summit in Portugal on Saturday by telling reporters that the Afghan government doesn't deserve a "dime" of direct foreign aid money until it cleans up its act on combating corruption.

Afghan President Hamid Karzai has asked NATO leaders and coalition partners to step up the flow of the billions of aid dollars to his government instead of filtering it through international organizations operating in the country.

But in his toughest criticism yet of the Afghan president, Harper indicated at the two-day summit that Canadian aid will not come without conditions.

"We will not dispense a dime to the government of Afghanistan unless we are convinced that that money is spent in the way it's intended to be spent," Harper said.

The prime minister told reporters that it is no secret Afghanistan's government has "challenges."

"But addressing those challenges can not stand in the way of the necessity, the absolute necessity of addressing the core reason of why we went into Afghanistan. And that is assuring that Afghanistan is a secure enough state capable of handling its own security so it does not again become a global threat. That is job number one."

U.S. President Barack Obama admitted at the summit that there are "real tensions" in the relationship with Karzai.

"He's also got to pay attention to our concerns as well. I don't think that's unreasonable," Obama said. "There is going to have to be a constant conversation to make sure we're moving in the right direction. And sometimes that conversation's pretty blunt."

Despite public disputes with the Afghan president, however, Obama said the U.S. and its NATO allies have aligned their aims for stabilizing the country under Karzai's administration.

Timeline questions

NATO leaders also agreed at the meeting to begin handing over control of security back to Afghans, with the country's military and police forces taking over almost completely by the end of 2014.

By the conclusion of the summit, leaders of the 28-nation military alliance settled on an exit strategy from Afghanistan, as well as the plan for training Afghan security forces in the years ahead.

Obama ended the meeting by saying for the first time that he wants American troops out of major combat in Afghanistan by the end of 2014.

"My goal is to make sure that by 2014 we have transitioned, Afghans are in the lead and it is a goal to make sure that we are not still engaged in combat operations of the sort we're involved in now," he told a closing news conference.

But the other members of NATO had different interpretations about the meaning of the 2014 target.

NATO Secretary-General Anders Fogh Rasmussen said that the alliance will not hand over the reigns of control "until our Afghan partners are ready."

"We will stay after transition in a supporting role," Rasmussen told reporters in Lisbon, Portugal where the summit was held.

"President Karzai and I have signed an agreement on a long-term partnership between NATO and Afghanistan that will endure beyond our combat mission. To put it simply, if the Taliban or anyone else aims to wait us out, they can forget it. We will stay as long as it takes to finish our job."

Rasmussen said he did not anticipate soldiers from the NATO-led International Security Assistance Force remaining in a combat role to fight the Taliban beyond 2014, "provided of course that the security situation allows us to move into a more supportive role."

But he did not specify when NATO may begin a draw-down of combat troops and added that an agreement had been signed with the Afghan government calling for NATO to remain in the country well past 2014 to assist with training and other duties.

But Britain has been adamant that its military role in the country will end by 2015.

"There will not be British troops in large numbers and they won't be in a combat role" by 2015, British Prime Minister David Cameron said. But he added, however, Britain has no intention of abandoning Afghanistan any time soon.

"We may be helping to train their army, we may still be delivering a lot of aid, in effect, because we don't want this country to go back to being a lawless space where the terrorists can have bases," Cameron told Sky News television.

Canada's mission

Last week, Ottawa announced that Canada's military mission in Afghanistan will be extended past the scheduled July 2011 pullout date, with up to 950 military trainers and support staff remaining in the country until March 2014.

Government ministers have repeatedly stressed that Canadians will be playing a non-combat role in Afghanistan during the extended mission. It is unclear if the government will look at extending the training mission until the end of 2014 in the wake of Saturday's announcement.

Karzai hailed Canada's ongoing commitment to Afghanistan on Saturday.

"Canada has been at the forefront of assistance to Afghanistan from the very beginning," he told reporters. "The Afghan people are extremely grateful to the Canadian contribution to the well being of the Afghan people."

Karzai said Saturday he has told the summit that Afghans still have concerns about a range of issues, from civilian casualties to detentions. But he praised the announcement, and promised the support of the Afghan government and citizens for a successful transition.

"We are confident that the transition will succeed to the Afghan authority, leadership and ownership, because I found today strong commitment by the international community," Karzai told reporters. "This strong commitment by the international community will be matched by determination and hard work by the people of Afghanistan. The two combined will give us the result of an effective, irreversible and sustainable transition."

Rasmussen said the process of transferring responsibility for the country's security back into the hands of Afghan forces will begin with them taking the lead on security operations in certain districts and provinces in 2011. The goal is for Afghan forces to be in complete control by the end of 2014, he said.

"To achieve that goal, we must train and educate Afghan soldiers and Afghan police, and therefore our training mission is crucial," Rasmussen said. "In that respect, it is encouraging that we have heard announcements that several allies and partners will provide more trainers. It is indeed a strong commitment to our mission and it's a strong commitment to the transition process, because trainers are the ticket to transition."

Rasmussen said NATO's training mission began last year and there are now more than 260,000 Afghan military and police personnel. The goal is to get that number to 300,000 by the end of next year, he said.

According to Rasmussen, 85 per cent of Afghan soldiers are partnering with international troops on various missions, and he said their progress makes him certain that NATO can meet its new security handover deadline.

UN Secretary General Ban Ki-moon stressed that international partners in Afghanistan have the same goals: "stability, reconciliation, good governance, respect for human rights and harmonious relationships between Afghanistan and her neighbours."

But he cautioned that long-term stability in Afghanistan cannot come from military solutions alone.

"Afghanistan's stability and wellbeing depend on a genuine political dialogue amongst all Afghans aimed at resolving the country," Ban said. "The Afghan search for a political solution has only entered its initial stage.

"As we move ahead, we must be guided by realities, not schedules….There are no shortcuts to peace."

It remains far from sure, however, that even an expanding and improving Afghan army will prevail without U.S. combat support.

With files from The Associated Press