Talks have broken down between Toronto Zoo and hundreds of its workers after the union that represents them walked away from the bargaining table.

In a press release issued Saturday, the zoo claimed it put forth a "reasonable compromise" to end the strike which has been ongoing since May 11, when some 400 CUPE 1600 employees hit the picket line. Its management team has been caring for the zoo's 6,000 animals in the meantime.

The development comes after a more than three-hour-long meeting on Friday, when, according to the zoo, the union suggested the two parties were 95 per cent of the way toward a settlement.

"Today's proposal, which maintains the current level of job security for all existing employees, should have provided that last 5% and allowed striking employees to return to work," zoo management said in the release.

The union has said they're worried that the zoo's board of management — which includes four city councillors — is trying to strip away job security language and avoid renewing a clause that guarantees a minimum workforce of 150.

Management has argued the union's proposals are not affordable.

Workers say zoo management has refused to explain why it's pushed for changes to the language around staffing.

"It is incredibly frustrating and disappointing," CUPE 1600 President Christine McKenzie said in a statement released Saturday.

"The union wants to see … good-quality, permanent, full-time jobs stay at the zoo," he told CBC Toronto on Friday, adding it's for both safety reasons and to make sure the zoo continues to be a "national leader in conservation science."

Zoo management says its proposal included protecting all current employees in the bargaining unit from "contracting out" — along with new employees after 11 years of service. It also included keeping the employer paid pension plan, existing vacation time and continuing its health and dental benefits plan.

The breakdown means the zoo will remain closed as workers continue to strike, leaving families who may have been hoping to visit this May long weekend out of luck.

While zoo management say they are committed to reaching a "fair and reasonable agreement" and ready to return to the bargaining table, that's not likely to happen this weekend.

No further talks are scheduled as of yet and while the union says it is available to restart talks, McKenzie says, "We will not bargain with ourselves or trade away the rights of future generations of Toronto Zoo employees."