OTTAWA, Sept 18 (Reuters) - Canada's Liberal government, trailing in the polls amid complaints about the high cost of living, on Monday said it would soon introduce wide-ranging draft legislation designed to help curb inflation.

Prime Minister Justin Trudeau last week announced a tax break designed to boost the construction of new rental apartment buildings and relieve pressure on the Canadian housing market.

Later on Monday, the heads of major grocery chains will meet government ministers who are demanding to see a plan to counter soaring food prices. Trudeau says Ottawa could impose extra taxes on the grocers and will remove provisions in the Competition Act that companies have used to defend big mergers.

"When it comes to housing, when it comes to groceries, when it comes to the Competition Act, this will be presented imminently ... in a comprehensive bill," said Karina Gould, the minister in charge of pushing the government's agenda through the House of Commons lower chamber of parliament.

Polls show that the official opposition Conservatives, who blame Trudeau for high inflation and a shortage of housing, would win an election if one were held now and end eight years of Liberal rule.

Canadian retailers say they are not to blame for surging food prices, and instead point to food manufacturers and producers for passing on higher costs to the grocers.

The grocery chains attending the meeting in Ottawa are Loblaws, Sobeys, Metro, Walmart and Costco, which together represent 80% of the Canadian market. (Reporting by Steve Scherer and David Ljunggren; Editing by Bernadette Baum)