Supermarkets should freeze the price of leg ham to give families certainty ahead of Christmas Day, federal Agriculture Minister Murray Watt says.

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

On Monday, Watt 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 with Christmas being a tough time for those struggling with cost of living pressures, he said.

“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,” he said.

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 an 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 the 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.”

McKim said “something’s not right” in the supermarket sector.

“It’s impossible to run through the supermarket aisles and arrive at the checkout at the moment without being aghast at the dollar value of what’s in your shopping trolley, and I have no doubt that millions of Australians are really struggling with massive price spikes on food and groceries,” he said.

“This is not just about people shopping, it’s also about the price they pay to people like farmers in Australia for their products. So we want to come to grips with what is causing this massive spike in food and grocery prices [while] the big supermarket corporations are raking in billions of dollars in profits, and we want to recommend action to bring food and grocery prices down in Australia.”

Farmers have also welcomed the inquiry. National Farmers Federation president David Jochinke said it was an opportunity to ensure small to medium farming businesses were being treated fairly by larger players.

“We know what Australians are paying at the checkout, and we know what we’re receiving as farmers – but who clips the ticket in the middle is shrouded in secrecy. We’d like to see a lot more transparency,” he said.

“Competition is a major issue in our supply chains and it’s a drag on productivity for the broader economy.

“Shining a light on how supermarkets use their market power is a positive step. But it can’t become a reason to delay action on broader competition policy reform.

A Woolworths spokesperson said the company was committed to offering customers value at the same time as it was helping suppliers manage economy-wide inflationary pressures.

“We know Australians are feeling the strain of cost of living and we are working to deliver relief in their weekly grocery shop,” the spokesperson said.

The company also flagged promotions on 150 Christmas products that kicked off in October, as well as a deal to lower the price of a half leg of ham to $8 a kilo, its lowest price in nine years.

A Coles spokesperson said the rate of inflation across its goods had been moderating, particularly for staples.

“Having a profitable business means Coles can continue to serve Australians, invest in our stores, employ the 120,000 team members we employ, pay taxes in Australia, pay dividends to our hundreds of thousands of mum and dad shareholders and ensure long-term sustainable relationships with our suppliers,” the company said.

Nationals leader David Littleproud said a parliamentary inquiry would take too long when immediate action was needed to address the cost of living. He has pushed for the consumer watchdog to investigate price gouging.

-with AAP