STRASBOURG, France - An aging NATO alliance already racked by divisions over direction began its 60th anniversary summit Friday bedevilled by a new challenge in Afghanistan.

News that the government of Afghan President Hamid Karzai has signed a law that would curtail the rights of Shia women is provoking outrage among reluctant European NATO contributors.

Jaap de Hoop Scheffer, NATO's secretary general, said the law makes it all the more difficult to muster scarce resources for the conflict -- even as U.S. President Barack Obama arrives at his first NATO summit with a sweeping plan to beef up the alliance's presence.

"The more capability we see here in Europe, the happier the United States will be," Obama said Friday in Strasbourg. "This is a joint problem that requires joint effort."

But de Hoop Scheffer said the Afghan law cripples efforts to sell a larger NATO role to skeptical European audiences.

"How can I defend this, and how can the British defend this, when our boys and girls are dying there in defence of universal values, and here is a law that fundamentally violates human rights?" he told the British Broadcasting Corp.

"The Afghan government should be realizing that we are there to defend universal values. And when I see at the moment a law threatening to come into effect which fundamentally violates womens' rights and human rights, that worries me."

NATO's long, draining mission in Afghanistan was already set to dominate this weekend's summit on the French-German border.

Prime Minister Stephen Harper arrived Friday from the G20 economic meeting in London, but declined an opportunity to speak to Canadian reporters before he headed to a NATO leaders' dinner in Baden Baden, Germany, about 40 kilometres from the main summit site on the Rhine River.

Foreign Affairs Minister Lawrence Cannon held a brief media availability in Strasbourg in which he questioned whether any such Afghan law "was adopted in the legitimate way and manner" of Afghanistan's national assembly.

Cannon said two Karzai ministers pleaded ignorance this week, and the ambassador to Canada has been called in for an explanation.

"If the media reports are true, this is extremely alarming," said Cannon.

But when asked about the impact such a law could have on mustering ongoing Canadian public support for Afghan reconstruction, the foreign minister repeated a rote talking point about Canada's 2011 combat mission end date and was then whisked away by media handlers.

Opinion in Canada, which has lost 116 soldiers in Afghanistan over seven long years, is already deeply divided.

Speaking about NATO's mission in Afghanistan, Harper conceded in an interview with Britain's Sky News: "We have been losing ground the last several years."

"I think NATO has to be successful in this enterprise and I do believe that the enhanced engagement, particularly by the Americans, is critical to turn this around," he told Sky News in London this week.

Harper, once a strong proponent of Canadian involvement in the U.S.-led Iraq war, also told the interviewer he now considers Iraq "a diversion from the central, original mission to Afghanistan."

Harper's defence minister, Peter MacKay, said in a pre-summit interview that NATO "is at a transformative point" and that success in Afghanistan is the alliance's "litmus test."

Conceived as defensive bulwark against Soviet expansionism in 1949, NATO has become a sprawling -- and in MacKay's eyes "bureaucratized" -- body that needs a revitalized "strategic plan."

"Clearly it is a body that has to be an expeditionary force, not just guarding the continent," MacKay told The Canadian Press.

That puts Canada on one side of an argument -- epitomized by NATO's expeditionary gambit in Afghanistan -- that has severely strained the alliance's all-for-one underpinnings.

There are about 70,000 foreign troops in Afghanistan, roughly half of them American.

Obama, having just committed another 21,000 U.S. troops to the mission, will be imploring his European allies to ante up, if not with combat troops then with aid, reconstruction and training.

"The most important support we could use right now is support in the civilian area," Admiral Mike Mullen, chairman of the U.S. joint chiefs of staff, said Thursday in Washington.

Several European countries made a show of announcing more support for the Afghan mission on Friday, but the numbers were small.

Britain said it would add "mid to high hundreds" to the 8,000 troops it has in Afghanistan. France promised more police trainers and civilian aid, and Belgium said it will add 65 soldiers and two more F-16 fighter jets.

MacKay said there will be much discussion this weekend about the practical implications of having "perhaps an even bigger distortion in terms of what the actual (U.S.) participation is" in Afghan mission.

"Other countries shouldn't just sigh and shuffle their feet and say, 'OK, the Americans have come now.' They should say, how can we dig a little deeper as well?"

Choosing the next secretary general will also be on the agenda this weekend, and Cannon said Canada "would be gratified" if MacKay -- a longshot compromise candidate -- was chosen.

NATO expansion and the alliance's relations with Russia are also on the table, two issues that are tightly linked.