OTTAWA (Reuters) - The number of Canadians leaving to join militant groups in Iraq and Syria such as Islamic State has increased 50 percent in the past few months, a senior security official said on Monday.

Canadian Security Intelligence Service (CSIS) director Michel Coulombe waits to testify before the Commons public safety and national security committee on Parliament Hill in Ottawa October 8, 2014. REUTERS/Chris Wattie

“The terrorist threat to Canada’s national security interests has never been as direct or immediate,” Michel Coulombe, head of the Canadian Security Intelligence Service spy agency, told a Senate committee.

Canada is part of the coalition of countries that has been bombing Islamic State, which controls large parts of Iraq and Syria and wants to redraw the map of the Middle East.

Coulombe was testifying about draft legislation the government unveiled in January that would give CSIS more powers to disrupt terror attacks and prevent Canadians from leaving to join militant groups abroad.

The total number of Canadians who have gone to Iraq and Syria to fight has jumped to 75 in the past three or four months from around 50 people, Coulombe said.

He did not give a reason for the increase or say how his agency got the information or why it did not stop the Canadians from leaving.

Last October, Coulombe said about 145 Canadians had traveled abroad to take part in terrorism-related activities during an unspecified period of time.

Police filed charges on Monday against two 18-year-old Montreal residents who authorities say were “attempting to leave Canada to participate in activity of a terrorist group”.

Sabrine Djermane and El Mahdi Jamali are in preventive detention. Police also charged the two with “facilitating terrorist activity” and using explosives.

Last month, Canada said it had foiled a plot by a self-proclaimed Islamic State supporter to bomb the U.S. consulate and other buildings in Toronto’s financial district.

Asked how long Canada would be combating potential domestic attacks by Islamic State supporters, Coulombe replied: “That is a threat we will have to deal with and manage with for a long time.”