OTTAWA - A C$1.25 billion Canadian program to help young people buy their first homes in a hot housing market will start up on Sept. 2, most likely just before an election is called, officials indicated on Monday.

The Liberal government of Prime Minister Justin Trudeau announced the measure in its March budget and at the time said it would come into effect in September. The Liberals, trailing the Conservatives in opinion polls ahead of an Oct. 12 federal vote, look set to formally launch the election in mid-September.

The three-year program will allow first-time buyers to finance a portion of their home purchases through a shared equity mortgage with the Canadian Mortgage and Housing Corporation (CMHC).

The government said this would encourage the construction of much-needed new housing supply at a time when many would-be buyers of moderate means complain homes are unaffordable.

"This will mean more money in the pockets of Canadians and will help up to an estimated 100,000 families across Canada," Families Minister Jean-Yves Duclos told a news conference.

Officials on a conference call with reporters later in the day side-stepped questions about whether the timing of the program was linked to the election, saying Sept 2 was the earliest it could start.

(Reporting by David Ljunggren; Editing by Susan Thomas) ((david.ljunggren@thomsonreuters.com; +1 613 235 6745; fax +1 613 235 5890; Reuters Messaging: david.ljunggren.reuters.com@reuters.net))