By David Ljunggren

OTTAWA, April 14 (Reuters) - Canadian Prime Minister Justin Trudeau, on the defensive over his government's handling of a controversial arms deal with Saudi Arabia, on Thursday said Ottawa would more closely probe future contracts to export weapons.

The affair marks the first notable misstep since the Liberals swept to power last November, promising a new era of openness and transparency.

One opposition party took the unusual step of saying the Liberals had lied about the $13 billion contract with General Dynamics Corp GD.N , which was signed in 2014 under the former Conservative government.

The Liberals stressed they had no choice but to honor what they said was a binding contract for light armored vehicles, despite concerns about the Saudis' human rights record.

But in response to a lawsuit by critics of the deal, Ottawa on Tuesday released documents showing Foreign Minister Stephane Dion had only last week signed the most important expert permits, which indicated Trudeau had a chance to veto the deal, but elected not to do so.

Trudeau told a news conference that the world needed to know that when Canada signed a deal, it would be respected even when the government changed.

But he also said that Ottawa would in future be open and transparent so "Canadians will be reassured on any new contract signed that we are doing a better job than perhaps the previous government did on respecting our principles, our values and indeed our laws."

Trudeau did not give details.

Ipsos Public Affairs pollster Darrell Bricker said the affair was "a little elite in its orientation," and therefore unlikely to cut into Trudeau's current high levels of popularity.

Former Conservative minister Tony Clement, in cabinet when the 2014 deal was signed, said the Liberals were not being honest and looked as though they had something to hide.

"It's the ultimate hypocrisy to promise more openness, promise more transparency than the previous government ... and the way we find out about the deal going through and the export permits being signed is through court documentation," he said by telephone.

Thomas Mulcair, leader of the opposition New Democrats, on Wednesday told reporters "the government lied to Canadians about who signed what when in the Saudi arms deal, and that is a very serious matter."

Canadian politicians rarely accuse each other of lying outside the House of Commons, where speech is protected.

(Reporting by David Ljunggren, editing by G Crosse) ((david.ljunggren@thomsonreuters.com; +1-613-235-6745, fax +1-613-235-5890; Reuters Messaging: david.ljunggren.reuters.com@reuters.net))

Keywords: CANADA POLITICS/TRUDEAU