The union representing York University's teaching assistants have voted go on strike Tuesday. They will join the already-striking University of Toronto workers.

CUPE Local 3903, which represents TAs, research assistants and contract faculty at York, was presented with a tentative agreement Monday evening. It was rejected hours later.

At issue for York's TAs is a funding package worth approximately $16,000 per year, which they say leaves them living below the poverty line.

Following Monday night's vote, York's president, Mamdouh Shoukri, issued a statement calling the strike "unfortunate." He said the majority of classes have been temporarily cancelled.

"To provide clarity to our students for the duration of the strike, we have regrettably suspended classes, with limited exceptions," he said.

The school's facilities, including the libraries, residences, computer labs, cafeterias and athletic centres, however, will remain open.

Previous strikes at York have caused long delays for students. When CUPE 3903 walked off the job in December 2008, the strike dragged on for three months.

Earlier on Monday, dozens of people walked the picket lines at three University of Toronto campuses after an agreement between the school and the union was rejected last Friday.

The 6,000 striking workers at Canada's largest school include teaching assistants, markers, graduate student instructors and lab assistants, all of whom are members of CUPE Local 3902.

The union's bargaining committee reached a tentative agreement with U of T early Friday morning, but the deal was rejected during a meeting that afternoon, before it even went to members for a vote.

The union members are graduate students who work part-time for the university for approximately $15,000 a year, at a rate of $42 per hour. The university offered to raise students' hourly pay to $43.97 (approximately $15,700 per year) and add vacation pay. The union is hoping for a salary closer to the $23,000 low-income cut-off set by Statistics Canada as a living wage for single workers in major cities.

"All we want really is to live at the minimum living wage in Toronto," one striker told CTV Toronto. "We're expected to be full-time researchers, part-time TAs and we're expected to do that on $15,000 a year."

The union says that teaching assistants provide 60 per cent of the undergrad instruction at U of T.

U of T students have been told that classes will go ahead, but they have also been warned there may be some strike-related interruptions to labs and tutorials.

Students at the downtown campus told CTV Toronto that the effects have been minimal so far, but Monday was the first day of the strike.

On Friday, the administration said students should expect it to take longer than normal to get to classes during the strike.

Students remain responsible for fulfilling course requirements, even if they choose not to cross picket lines in solidarity with those on strike, officials said.

With a report from CTV Toronto's Zuraidah Alman