Canada opposition raps planned fighter jet contract

* Opposition vows to put deal on hold if it wins power

* Government to announce big contract on Friday

OTTAWA, July 15 (Reuters) - Canada's main opposition Liberal Party condemned a multibillion-dollar government plan on Thursday to buy a fleet of new fighter jets from Lockheed Martin Corp (LMT.N).

The Conservative government said in May 2008 that it planned to buy 65 of Lockheed's F-35 Joint Strike Fighters. Media reports say Ottawa will announce a C$16 billion ($15.4 billion) deal on Friday to buy the jets and maintain them for 20 years.

The F-35s would replace Canada's aging CF-18s, which are scheduled to reach the end of their working lives in 2017-20. Canada bought 138 CF-18s in the 1980s and has refurbished 80 of them.

Liberal industry spokesman Marc Garneau said there was no need to make an announcement about the new fighters now and questioned why the government would offer a sole-source contract.

"A future Liberal government will put on hold this ... contract," he told a news conference. "Competition guarantees the best value for Canadians."

Polls show the Liberals trail the Conservatives and would have little chance of winning an election now.

A spokesman for Defence Minister Peter MacKay said there would be a "major defence procurement announcement" in Ottawa on Friday but did not give further details.

The Joint Strike Fighter program is being funded by the United States, Canada, Turkey, Britain, Italy, Norway, Denmark, Australia and the Netherlands.

The JSF is set to be the world's costliest arms acquisition program, priced at more than $300 billion for the United States alone. The United States is scheduled to buy more than 2,400.

One rival aircraft is the Eurofighter, made by a consortium comprising Britain's BAE Systems (BAES.L), Italy's Finmeccanica (SIFI.MI) and EADS (EAD.PA), representing Germany and Spain.

($1=$1.04 Canadian) (Reporting by David Ljunggren; editing by Rob Wilson)