The United Food and Commercial Workers union says H.J. Heinz never approached it to find a way to keep the Leamington processing plant open.

UFCW Local 459 president Rob Crawford said the union would have been willing to work with the company.

“I would have asked, ‘what do we need to do to make this more profitable?’” Crawford said.

Crawford said he would have been willing to negotiate concessions if it meant 740 full-time employees could have kept their jobs.

The Leamington plant will close in June of next year. More than 700 people will lose their jobs.

“If that would have kept the plant in Leamington open, absolutely,” Crawford said of concessions. “We’ve worked with Heinz well. Whenever there was a problem, if they’ve approached us, we’ve worked through it. We would have done the same.”

On Tuesday, billionaire Warren Buffett says there is one main reason H.J. Heinz Co. chose to close its Leamington plant. Buffett's Berkshire Hathaway, along with 3G capital, bought H.J. Heinz Co. for $23.3 billion US earlier this year.

"It’s really a question of having an unprofitable plant and concentrating production in a more profitable plant. You see that in the auto industry," Buffett said Tuesday at appearance in Detroit.

Crawford said he wasn't aware the plant wasn't profitable.

"To the best of my knowledge, I thought the Leamington plant was a profitable plant," Crawford said. "I don’t have numbers, but like I said, no one approached us and said we weren’t profitable."

The closure could also affect up to nearly 50 farmers who sell tomatoes to Heinz. Although, Buffett isn't sure.

"The tomatoes are going to go to the plants that have the low production costs," Buffett said, referencing the 40-plus farmers who currently supply the Leamington plant.

The 104-year-old plant will close in mid-2014.

"Between now and next June, or there abouts, there’s going to be very generous severance arrangements made," Buffett said.

Buffett's Berkshire Hathaway, along with 3G capital, bought H.J. Heinz Co. for $23.3 billion US earlier this year.

Buffett is a member of the Heinz board of directors.

On Nov. 14, Heinz announced it will close three plants in North America, including Florence, SC (200 employees); Pocatello, ID (410 employees); and Leamington (740 employees).

In August, H.J. Heinz Co. eliminated 600 office jobs across the U.S. and in Canada, including 350 in Pittsburgh, nearly a third of its operation there.

"At the same time, Heinz will continue to invest in improving capacity utilization and will add 470 employees across five existing factories in Ohio, Iowa, California and Canada," Heinz spokesperson Michael Mullen said in an emailed statement to CBC News last week.

One of those plants is the Massillon plant in Ohio, where 249 jobs will be added.

"There will be jobs opening up in St. Marys as well," Buffett reaffirmed Tuesday in Detroit.

"I hope they continue to invest in plants, including the one in St. Marys," Crawford said. "But I’m of the understanding there aren’t any jobs there."