UPDATE 3-Union to vote again on Air Canada contract deal

* IAMAW union members to vote again after talks

* Clarifications were on job security

* Union members also to vote on a strike mandate (Adds union, analyst's comments)

By Nicole Mordant

VANCOUVER, British Columbia, July 6 (Reuters) - Members of Air Canada's (ACa.TO) biggest labor union, who rejected a tentative contract agreement with the carrier last week, will vote again on the offer on July 14 after the two sides talked over the weekend, a union spokesman said on Monday.

Air Canada, the country's biggest airline, said in a statement that it and the negotiating team from the International Association of Machinists and Aerospace Workers (IAMAW) had "agreed on the clarification of certain issues" in talks this past weekend. The two sides also agreed on a "prompt revote on the original agreements".

The union's negotiating committee and Air Canada reached a tentative 21-month agreement on June 8 on a new labor agreement, as well as a deal that will allow the cash-strapped airline to temporarily halt funding its C$2.9 billion ($2.5 billion) pension deficit.

But members of the 12,300-strong IAMAW narrowly rejected the agreements in a vote last week, a surprising outcome and a troubling one for the debt-laden airline.

Union support is critical for Air Canada to gain federal approval for a temporary freeze on pension funding and C$600 million in short-term loans.

Without a pension moratorium and the new financing, analysts say the carrier could be headed for its second bankruptcy filing in six years.

IAMAW spokesman Bill Trbovich said on Monday that union members across Canada will vote again on July 14, with results likely announced the same day.

The union said on its website that Air Canada, in a series of letters of intent and clarification, had at the weekend addressed member concerns on outsourcing, labor relations, pension matters and job stability at Aveos Fleet Performance, a sister company to Air Canada.

This is Air Canada's final offer, the union said.

As a result, union members will also be asked to vote on a strike mandate to give their leaders the right to strike if the agreement is voted down.

"If we had a sustained strike at Air Canada it would have a significant material negative effect on the company to the point where filing for CCAA (bankruptcy protection under the Companies' Creditor Arrangement Act) may have to be an eventuality," said CIBC World Markets analyst Chris Murray.

Air Canada was not immediately available for comment.