About 500 striking librarians have set up a picket line outside city hall on day one of the public library workers' strike.

Members of CUPE Local 4948 walked off the job at 5 p.m. Sunday after a marathon negotiating session with the Toronto Public Library Board failed to produce a tentative agreement.

Many of the union's 2,300 workers are now marching outside city hall and the Toronto Reference Library near Yonge and Bloor streets. Maureen O'Reilly, president of CUPE Local 4948, is expected to address the crowd gathered outside city hall around 12 p.m.

"The city is demanding that the only people covered by an employment security clause have 15 years of seniority and the only reason the city would be seeking such a measure is if they are seeking in a subsequent budget to sell off branches and reduce staff," picket captain Jonathon Hodge told CP24 outside city hall. "I think Torontonians should be deeply concerned about a reduction in the footprint of our library system, which is one of the most widely used in the world."

CUPE Local 4948 was in a legal strike position at 12:01 a.m. Sunday, but chose to remain at the table in the hopes of reaching a negotiated settlement.

Though some progress was made, CUPE Local 4948 spokesperson Cim Nunn told CP24 that the two sides continue to be far apart on major issues such as part-time worker rights and job security and are not currently talking.

"We had lots of opportunities for meaningful and productive negotiations and that just didn't happen; we stalled," he said. "We would much rather be talking than marching here, but the city has to take a different approach with us."

As long as the library workers are on strike all 98 public library branches in Toronto will be closed and all bookmobile and home delivery services will be suspended. Anyone who currently has items on loan from the library are being told to hold on to them until the strike is resolved. No late fees will be charged.

During a news conference Sunday evening, Coun. Paul Ainslie, chair of the Toronto Public Library Board, said he is still hopeful a deal can be done soon.

"If there is one thing Torontonians love it is their libraries and I would just encourage everyone to take a breath, take a step back and get back to the table and get a good deal for the future of our libraries," Coun. Paula Fletcher told CP24 outside city hall.

CUPE 4948 has been without a contract since midnight on Dec 31.