HALIFAX -- A mediator has been appointed in a bid to prevent a possible strike by 800 paramedics in Nova Scotia, which could come as early as this weekend.

Labour Minister Frank Corbett said Wednesday he has named John Clarke to help with negotiations between the unionized paramedics and their employer, Emergency Medical Care Inc.

Clarke is a veteran arbitrator and lawyer from St. John's, N.L., who has mediated numerous labour disputes.

The paramedics, represented by the International Union of Operating Engineers, Local 727, will be in a legal strike position Saturday.

Terry Chapman, the union's business manager, said Wednesday the union expects to meet with the employer and the mediator before the end of the week, but the company has yet to make contact.

"Unless the employer returns to us with something that will satisfy the membership ... then we intend to continue going forward, and we'll be in a legal strike position to withhold services on June 8," he said in an interview.

"We're not willing to commit to putting this off for another two weeks or a month just because the employer wants to sit at a table and do nothing."

Chapman said the outstanding issues include wages and the union's demand for defined-benefit pensions instead of defined-contribution plans -- something most other health-care providers in the province already have.

He said the union also wants a standard three-year deal instead of a five-year contract as suggested by the employer.

Last week, the paramedics rejected the latest contract offer from the company, which has a contract with the province's Emergency Health Services branch.

The company has said it has plans in place to deal with a strike.

When the province's paramedics walked off the job in October 1999, company managers stepped in to keep the service operating. But the strike didn't last long. The paramedics were legislated back to work after 18 hours.

The paramedics have been without a contract since 2011.

In early April, the union's bargaining committee recommended acceptance of a tentative deal, but the membership rejected it last month.