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 ( SU ), Imperial Oil ( IMO )

, Cenovus Energy ( CVE ), Enbridge ( ENB ) 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.