Canada backed away from a pledge to join the US Ballistic Missile Defense (BMD) system, US ambassador to Canada Paul Cellucci said in an interview aired Sunday.

The senior diplomat told a Canadian television that Canadian Prime Minister Paul Martin had been sending strong signals for some time that his country would participate in the anti-ballisticmissile shield program.

"We were given that impression in a very direct way for a long time," Cellucci said.

Martin announced late last month that Canada would not participate in the program, saying he would not back the "weaponization of space."

Washington has expressed disappointment over Martin's decision.US Secretary of State Condoleezza Rice reportedly canceled her trip to Ottawa scheduled for mid-April.The White House said Martin called US President George W. Bush on Saturday, and the two leaders exchanged views on Canada's decision to opt out of the plan.

"The president expressed understanding of Martin's decision but underscored the importance of redoubling our security cooperation efforts," White House spokeswoman Erin Healy said.

Martin denied Sunday that Canada was ever onboard the missile defense program.

According to the latest public polls, the US BMD plan is highly unpopular in Canada. A poll of more than 3,000 Canadians, taken late last year by the Center for Research and Information on Canada, found a majority of voters opposed to the scheme. In the province of Quebec, the opposing rate stood at almost 70 percent.

Members of every political party represented in the House of Commons are mostly opposed to, or uncomfortable with, the system.

Xinhua