U.S. President Barack Obama, right, listens to NATO Secretary General Anders Fogh Rasmussen during a meeting in the Oval Office of the White House in Washington on Tuesday. (Joshua Roberts/Reuters)

U.S. President Barack Obama met with NATO Secretary General Anders Fogh Rasmussen on Tuesday to talk about a possible new strategy in Afghanistan amid calls for more allied troops in the war-torn country.

Speaking to reporters in Washington after the meeting at the White House, Rasmussen said European leaders are studying a report presented by the U.S. and NATO commander in Afghanistan, Gen. Stanley McChrystal, last week. His report included a call for an additional 40,000 combat troops.

However, Rasmussen added, allied leaders must determine a strategy before allocating more resources. "The first thing is not numbers," he said.

Added Obama: "We both agree that it is absolutely critical that we are successful in dismantling, disrupting and destroying the al-Qaeda network."

Neither man took questions or referred to Iran.

Obama currently is considering U.S. options in Afghanistan, which include boosting military strength there to try to neutralize the Taliban and other extremists, or pursuing a new strategy of rooting out al-Qaeda militants in neighbouring Pakistan.

The latter option would involve few troops and more unmanned drones and special forces units. NATO contributes roughly two-thirds of the more than 100,000 international troops in Afghanistan, including more than 3,000 from Canada.

Rasmussen noted dwindling public support in ally nations for sending more troops to Afghanistan in light of massive fraud allegations, including ballot box stuffing and voter coercion, in the Aug. 20 presidential elections.

Preliminary results showed Afghanistan President Hamid Karzai winning with 55 per cent of the vote. But officials are now recounting 10 per cent of ballots and if enough are found to be fraudulent, Karzai could dip below the 50 per cent threshold needed to avoid a runoff with chief challenger Abdullah Abdullah, a former Afghan foreign minister.

Key Obama advisers have said it would be difficult for the U.S. to work with Karzai as president given the suggestion of fraud. However, William Crosbie, Canada's ambassador to Afghanistan, said he is confident that whoever forms the new government will have the support of the international community provided he delivers services to the Afghan people, tackles corruption and creates national institutions that are needed.

"At the end of the day, the credibility of any government is not going to rest on the electoral process per se, it's going to rest on the ability of a new government to demonstrate it can improve the situation in Afghanistan," Crosbie told CBC's As It Happens in an interview. "We cannot win the war for the … Afghan people. Ultimately success in the country in terms of bringing peace and security" rests with them.

Prime Minister Stephen Harper has maintained that Canada will pull its troops out of Afghanistan by 2011.

The White House is not expected to consider McChrystal's troop request for at least two weeks while Obama decides what strategy to pursue, a senior military official said.

With files from The Associated Press