Prime Minister Stephen Harper says Canada is considering a U.S. request for further military contribution in the fight against ISIS in Iraq.

Harper's comments came during a question and answer session with Gerard Baker, editor in chief of the Wall Street Journal, before a business audience in New York.

Asked by Baker if he would rule out "a directly military contribution" to any effort, Harper said no.

"I haven't ruled out — we haven't ruled out anything. We need to have some additional debate within our government before we reach a final decision, but we're wanting to see this be successful. And we want to be supportive as best we can."

A senior government source later told CBC News "there is no request, plan or intention to commit troops to combat."

Late Wednesday, Radio-Canada also spoke to Foreign Affairs Minister John Baird. "I don't think anyone in Canada has contemplated a ground combat role," he said.

Harper revealed, during the question and answer session, the U.S. had formally asked Canada in a letter received this week for further involvement in the fight against Islamic State militants in the Middle East.

"The United States has just recently, in the last couple days, has asked for some additional contribution and we'll — we're weighing our response to that."

When pressed for details of the U.S request, Harper said he preferred not to get ahead of the Americans.

"Since they didn't release the letter publicly, I'm not going to do that. I'll just say the government of Canada will make a decision on that very shortly."

Harper said the matter would be discussed in Ottawa.

"We'll be having some debates in cabinet and Parliament about what additional steps we may be willing to take, but I think this is a very important objective of the [U.S.] president," Harper said.

To date, Canada has deployed 69 special forces advisers in Iraq.

Vote in Parliament?

Harper's answers during the session in New York came just as question period was underway in Ottawa.

Moments after news of Harper's answer reached Parliament Hill, Opposition NDP Leader Tom Mulcair turned to James Bezan, the parliamentary secretary for the minister of defence, and asked whether Harper would put the U.S. request to a vote in the Commons.

"The prime minister has just stated in New York that the United States has requested additional resources from Canada in Iraq. The prime minister says he needs to have some debate in cabinet before he can make any decision on this file.

"Will there also be a debate and vote in the House of Commons?" Mulcair asked.

Bezan did not answer the question directly, saying only there would be "discussions" as Canada's 30-day commitment, which began on Sept. 5, comes to an end.

"We have been supportive of U.S. efforts in forming this coalition to take on and tackle ISIL, and that's why we have committed Canadian Forces in a non-combat role.

"We're coming up to the end of 30 days from Sept. 5, and we will have these discussions as we review our progress and look at renewing our commitment," Bezan said.

Harper vowed in a speech from the throne in 2007 "that any future military deployments must also be supported by a majority of parliamentarians."

The government's refusal to answer questions about Canada's deployment in Iraq boiled over on Tuesday when Mulcair appealed to House of Commons Speaker Andrew Scheer to referee the debate.

ISIS added to terrorist list

On Wednesday, U.S. President Barack Obama called on world leaders to rally behind a concerted effort to defeat ISIS — using both military force in Iraq and Syria and domestic intelligence and security forces to stop the recruitment of new fighters in western countries.

As result of Obama's intervention, members of the UN Security Council unanimously passed a resolution requiring all countries to toughen their laws to prevent foreign fighters from joining extremist groups such as ISIS.

British Prime Minister David Cameron said that the U.K. Parliament would be called back from its recess for party conventions to allow politicians there to debate a growing deployment to Iraq and Syria.

Harper spoke to the UN Security Council later in the day, where he told world leaders of Canada's preoccupation with the efforts of extremist militants in recruiting foreign fighters.

"The presence of large number of foreign fighters in Syria and Iraq is of course not only aggravating an already dangerous regional security situation, but for us it involves the risk that individuals may return home with knowledge and experience gained in terrorist activities to motivate and recruit others and potentially to conduct attacks."

"In Canada, our security and intelligence agencies work well and work most particularly well with our Muslim communities in identifying such threats," Harper said.

Approximately 160 Canadians are known to be fighting with foreign militant organizations, while another 80 are believed to have returned to Canada, according to a report by Public Safety Canada.

Harper laid out some of the initiatives that Canada has undertaken to thwart extremist threats, including a decision announced earlier Wednesday to update the list of groups it considers to be terrorist entities under the Criminal Code to include the Islamic State by name.

Obama, who was chairing the meeting for most of the day, left for another UN assembly minutes before Harper's turn was up.

The U.S. president thanked Harper, whom he called a "good friend," and other leaders for their participation​ and then turned the meeting over to U.S. Secretary of State John Kerry.

When Harper was in New York last September, he used a question and answer session with the Canadian American Business Council to tell Obama Canada would not take no for an answer on the Keystone XL pipeline.

On Wednesday, Harper said he was confident the pipeline would be approved "some time in the future."