His call comes as Coles and Woolworths look set to face a parliamentary inquiry into whether they are price gouging to get record profits amid cost of living pressures.

Senator Watt on Monday sent a stern warning to supermarkets to “not profit off hardworking Aussies” in the lead-up to Christmas.

Supermarkets should put a freeze on the price of leg ham, to give families certainty ahead of the big day, with Christmas being a tough time for those struggling with cost of living pressures, he said in a statement.

“The traditional ham is a staple of any Christmas lunch in Australia.

“And we know families are doing it tough at the moment and the cost of a lot of things is going up.

“It’s time for supermarkets to do their part and say one thing we won’t put up is the price of a Christmas ham”.

Senator Watt said farmers also needed certainty that they would get a fair price from supermarkets.

“For the average Aussie, it doesn’t make sense that the price on the bottom of their docket is going up while these companies are recording massive profits,” he said.

The Greens are seeking to establish a committee inquiry into the impact of market concentration on food prices and the pattern of pricing strategies employed by the supermarket duopoly.

Coles and Woolworths will be in the spotlight as the inquiry scrutinises the increasing cost of essential items, validity of discounts offered and profit inflations.

Greens senator Nick McKim said on the weekend that major supermarkets had had far too much power in Australia for too long.

“Coles and Woolworths are making billions in profits because they feel that they can overcharge people without repercussions (and) it needs to end,” he said.

“We want the CEOs to justify their decisions in a public hearing.”

Nationals Farmers’ Federation chief executive Tony Mahar said an inquiry was urgently needed.

“Farmers are worried and concerned that the prices they’re getting don’t or aren’t reflected on the supermarket shelves,” he told Seven’s Sunrise program on Monday.

“It would be really good to actually examine who’s clipping the ticket across the supply chain, and if there is gouging there, let’s do something about it.”

Mr Mahar said the current system in place was unsustainable for the farming sector.

“(The inquiry) is not going to be a silver bullet, it will take a few months … but what we hope it does is provide some recommendations to the government to strengthen competition policy,” he said.

Nationals leader David Littleproud said a parliamentary inquiry would take too long when action was needed now to address the cost of living crisis facing Australians.

He has pushed for the consumer watchdog to investigate whether price gouging was occurring.

But fellow Nationals MP Barnaby Joyce said an inquiry was needed.

“I’m 100 per cent for it … we need transparency of exactly what’s going on here,” he said.

Environment Minister Tanya Plibersek said it would be good to see more competition in Australian supermarkets.

“The two big supermarket giants made $2.7 billion worth of profits last year … it’s not because they’re making the farmers rich, so it’s well worth seeing what the problem is with the supermarket system in Australia,” she said.