TORONTO -- The union representing teaching assistants and other academic staff at Ontario's two largest universities warns a strike as early as Thursday could jeopardize the school year for thousands of students.

The Canadian Union of Public Employees says about 10,000 non-tenured academic staff at the University of Toronto and York University could walk off the job if they don't get a contract with a "modest" salary increase.

CUPE says teaching assistants provide about 60 per cent of the undergrad instruction at U-of-T and York, but account for only 3.5-to-eight per cent of the universities' operating budgets.

Union president Fred Hahn says teaching assistants get paid $15,000 a year -- $8,000 below the poverty line -- and they must pay tuition on top of that.

He says they also need increased job security, noting many don't know from one semester to the next if they will have a job.

CUPE negotiates directly with the universities, but Hahn says the province should provide special funding to help teaching assistants get a pay hike, just as it has done for low-income child-care workers.

"They've said they understand that low paid workers deserve a raise ... and that workplace precarity is an epidemic that they need to address," he said. "What we're pointing out here today is that the majority of instruction at two of the largest universities in our country is done by workers living below the poverty line who all suffer from workplace precarity."

CUPE represents about 240,000 workers across Ontario, including about 25,000 at the province's universities.