June 6 (Reuters) -

Canada's biggest oil sands producers support a paying a tax on carbon but see a proposed federal oil and gas emissions cap as unnecessary legislation, the companies' CEOs told lawmakers in Ottawa on Thursday.

Executives from Suncor Energy, Imperial Oil , Cenovus Energy, Enbridge and Shell appeared via videolink before a House of Commons committee to answer questions on their efforts to cut emissions.

The oil and gas sector is Canada's highest-polluting industry, accounting for more than a quarter of all emissions, and in 2022 made record profits as oil prices soared during Russia's invasion of Ukraine. Climate campaigners say companies should invest more of their profits in decarbonization.

Prime Minister Justin Trudeau's Liberal government is planning to introduce a cap on the sector's emissions but faces stiff opposition from the industry, which argues the legislation in unnecessary because Canada already has regulatory incentives in place, including a price on carbon produced by industry.

"I do support a price on carbon across the economy because I believe that will drive the innovation, the economic incentives on all of our part to continue to improve our business," said Suncor CEO Rich Kruger.

"I fundamentally worry that a cap on emissions, the way it's constructed, will be a cap on production," he added.

Canada is the world's fourth-largest oil producer. (Reporting by Nia Williams in British Columbia Editing by Marguerita Choy)