Canada has until next April to tell NATO whether it plans to extend its combat mission in Afghanistan, Defence Minister Peter MacKay said Monday.

MacKay, who spoke to reporters while campaigning for a provincial Conservative candidate in Ottawa, said Canada must deliver its answer at a NATO summit in Romania in April 2008.

"It will be necessary to communicate a final decision before that meeting," said MacKay.

All three opposition parties have demanded the government clearly commit to ending the combat mission when Canada's international commitment to the NATO-led mission expires in February 2009.

Harper has said the soldiers should leave when they have finished the job they were sent to do.

The prime minister has said the issue will be put to a vote in the House of Commons. Earlier this month, Harper said he didn't plan to hold a vote until he could find enough support to let the troops "finish the job."

The Liberals said earlier this summer they will use an opposition day to call for a vote on the matter when the House of Commons returns in October.

Opposition House leader Ralph Goodale said on Monday that April 2008 doesn't give NATO enough time to find a replacement for Canada. Liberal Leader Stéphane Dion has repeatedly said NATO must be given notice now so that an orderly transition can take place.

"If that is the date, that's only nine or ten months before the scheduled end of the mission," said Goodale.

"The notice needs to be given to NATO now."

Goodale also accused the government of being deliberately ambiguous.

Earlier this month, MacKay said during a television interview that Ottawa has already signalled to NATO that "our current configuration will end in February 2009."

A Defence official later said there has been no new signal sent to NATO and that there would be a vote in Parliament.