* Seek deal between airline, flight attendants

* Mediators have June 22 deadline

* Air Canada shares close 1.8 percent lower (Adds details, WestJet pilot contract)

By Susan Taylor

OTTAWA, June 17 (Reuters) - The Canadian government appointed two mediators on Wednesday to help Air Canada (ACa.TO: Quote, Profile, Research) and the union representing its flight attendants to reach a labor agreement.

The Canadian Union of Public Employees, which represents about 6,700 flight attendants at the country's biggest airline, said talks broke off early Tuesday because the cash-strapped carrier's proposals would reduce wages for some staff and lead to job losses for others.

CUPE is the lone holdout in contract talks as the company's four other unions have reached tentative deals that will freeze wages and pension benefits for 21 months.

The government named former Ontario Superior Court Judge James Farley, already working to settle pension disagreements between the airline and its unions, and Quebec's regional director of the federal mediation and conciliation services, Jacques Lessard, as the mediators. They have until noon on Monday June 22 to work out a labor deal.

At that time they can make recommendations for the settlement of any remaining differences between the parties.