If Montreal-based aerospace manufacturer Bombardier Inc. needs federal money to aid its CSeries jet project, it'll have to make a "strong business case," Prime Minister Justin Trudeau told a meeting of labour leaders Tuesday.

Trudeau was responding to questions at a closed-door Canadian Labour Congress gathering in Ottawa — the first time a sitting prime minister has addressed the country's biggest labour body in more than 50 years.

He told the CLC's Canadian council that his government won't prop up a business on the basis of emotion or politics, sources inside the room disclosed.

Trudeau did, however, characterize Bombardier as a high-value manufacturer in the same league as the auto sector, which received government money to help it get through the 2008 recession.

"There's no question that high-value manufacturing is going to be an extremely important part of Canada for years to come. Aerospace is a great example of that, as is the auto sector and others," Trudeau told the gathering.

"How we can best invest and support that kind of manufacturing needs to be done responsibly and with our eyes open, and not just based on emotion or politics or symbols," he said.

"There has to be a strong business case. We're going to make sure that decision is taken based on what is in the best interest of Canadians, writ large."

Quebec in, lobbying feds

The Quebec government said last month it would invest $1 billion in the CSeries in return for a near 50 per cent stake in the project.

Since then, the province has been lobbying Ottawa to match the contribution.

The project has saddled the company with debt, forcing it to into a struggle to raise cash in order to keep it afloat.

Transport Minister Marc Garneau, who represents a Quebec constituency, has said Bombardier has not formally approached the government about possible federal aid.

Trudeau's comments about Bombardier came as no surprise, said CLC president Hassan Yussuff.

"I think Bombardier's got a good, strong argument regarding the business case," Yussuff said after the prime minister spoke.

"Bombardier's got a large footprint across this country in terms of jobs and community and I think it's very important to maintain that."

'Anti-union' bills to be repealed

The last time a prime minister appeared in front of the Canadian Labour Congress was when John Diefenbaker spoke at the organization's 1958 convention.

Trudeau was loudly applauded when he told Tuesday's meeting of more than 120 labour leaders that his government will fulfill the Liberal campaign promise to repeal Bills C-377 and C-525 — the former Conservative government's anti-union legislation.

Trudeau said he recognizes that "labour is not a problem, but a solution."

The prime minister also welcomed a pledge from the CLC to help in dealing with climate change and the Syrian refugee crisis.

"We have more than 130 labour councils and 25,000 union locals in communities across Canada and we've made it clear to the prime minister that we want to do our part in helping his government meet its goal to welcome and resettle 25,000 Syrian refugees to Canada," said Yussuff.