WASHINGTON – Canadian Prime Minister Stephen Harper has announced plans to hire 1,400 border guards and Royal Canadian Mounted Police, addressing longtime criticisms that his nation’s immigration policies have made the country a haven for terrorists.

Harper’s plan, unveiled Wednesday and Thursday, also calls for arming border security officers over the next 10 years, beginning next year.

Proponents of tough U.S. immigration enforcement have called for tighter controls on the Mexican border, but they’ve also voiced concern that Canada’s sparsely patrolled border provides terrorists with an unimpeded gateway to America.

“The northern border is a concern, because it’s double the size of the southern border and it’s virtually unprotected,” said John Keeley, spokesman for the Center for Immigration Studies in Washington.

But the measures already are sparking a debate in Canada over whether they’ll help bolster security in a post-Sept. 11 world or needlessly militarize the 4,000-mile U.S.-Canada border.

“It’s extremely controversial for a lot of Canadians,” said Janet Dench, the executive director of the Canadian Council for Refugees. “We like to think of our country as welcoming to people who arrive at our border.”

Harper’s announcements come on the heels of the breakup of two alleged Toronto-based terror plots.

In early June, the RCMP arrested 17 young men and teenagers in an alleged scheme to take hostages in the Canadian Parliament and bomb buildings in southern Ontario. In late August, the United States and Canada announced that they’d foiled a plot by at least nine U.S. and Canadian residents to buy and ship arms to the Liberation Tigers of Tamil Ealam, a violent Sri Lankan separatist group.

“A safe, secure and efficient border is important for Canada, and for all Canadians,” Harper said Thursday in Surrey, British Columbia.