OTTAWA (Reuters) - The leader of Canada’s opposition Conservative Party said on Sunday that Prime Minister Justin Trudeau threatened to sue him for libel over statements made about a scandal that has dogged Trudeau and his ruling Liberal Party for two months.

The Liberals have been in turmoil since former Justice Minister Jody Wilson-Raybould said in February she had been inappropriately pressured to ensure that construction company SNC-Lavalin Group Inc escape a corruption trial.

In a bid to quell the crisis that has hurt his chances for re-election in October, Trudeau last week expelled from the Liberal caucus Wilson-Raybould and former Treasury Board chief Jane Philpott, who also has criticized the handling of the SNC-Lavalin affair.

On Sunday, Conservative leader Andrew Scheer released a letter he said he received a week ago from a lawyer representing Trudeau. It referred to statements made by the opposition leader on Facebook on March 29, which the letter called “beyond the pale of fair debate” and “libelous.”

The letter is to be “treated as a notice” and will be referred to “in any subsequent action,” it said.

The Conservatives have repeatedly accused Liberals of trying to “interfere in ongoing court proceedings,” and have sent a letter to federal police urging them to launch a criminal investigation.

In response to the opposition leader’s comments, the prime minister’s office said in a statement on Sunday: “Andrew Scheer and the Conservatives have repeatedly made false and defamatory statements. We put him on notice that there are consequences for making completely false and libelous statements.”

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Scheer said the prime minister’s complaints were “without merit,” adding he hoped the libel case was brought “immediately” because it would mean Trudeau would have to testify publicly and under oath.

“I believe this is an attempt to stifle criticism of Justin Trudeau. This is a bullying attempt to try to prevent me from doing my constitutional duty as leader of the opposition,” Scheer told reporters.

Although far from routine, Canadian political leaders have sued rival politicians for libel in the past for remarks made outside Parliament, where comments are immune from prosecution.

Wilson-Raybould says officials urged her to overrule prosecutors who insisted SNC-Lavalin must face trial on charges of bribing Libyan officials between 2001 and 2011. The firm wanted to take advantage of a law passed last year allowing it to escape with a fine.

Trudeau has denied any wrongdoing, saying he and officials had wanted to make sure Wilson-Raybould understood the potential for job losses if SNC-Lavalin were found guilty.