The Conservative Party machinery isn't letting rogue MP Maxime Bernier leave with any party favours.

The Tories' lawyers sent Bernier a letter Tuesday warning him not to use any party member lists — a valuable tool for fundraising and speaking directly to activists — now that he's left the party.

Radio-Canada, CBC's french-language arm, obtained a copy of the letter. In it, lawyer Arthur Hamilton, counsel for the Conservative Party of Canada and the Conservative Fund Canada, asks Bernier to return any lists he received, maintained and supplemented during his leadership run.

Hamilton also asks Bernier to confirm he didn't consult any such lists when he announced he'd be leaving the Conservative banner to start his own national party late last week.

"We require immediate notification of the circumstances of such use, and the full scope and particulars of what exactly that use entailed," reads the missive.

"You are hereby advised that we take all necessary steps to protect the personal information and privacy of our members and donors."

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A source close to the Bernier , who spoke on the condition of anonymity, called the letter "an intimidation attempt" and said the Quebec MP returned his list of party members at the end of the leadership race.

The source also told Radio-Canada that Bernier has about 30,000 addresses through his own website, which uses NationBuilder to manage his database.

"All the addresses we have, have been collected separately," said the source.

but said he began putting things in motion more than a week before that following a conversation with Conservative Leader Andrew Scheer regarding Bernier's recent string of controversial tweets. Bernier, who represents the Quebec riding of Beauce, announced his departure from the party on Thursday,

Battling the party

He said he had to leave because his former party is "too intellectually and morally corrupt to be reformed," and under Scheer's leadership, it has failed to stand up for conservative principles like dismantling supply management and opposing retaliatory tariffs in the trade dispute with the U.S.

The plan, said Bernier, is to have the federal party up and running in two to three months.

While he isn't expecting anyone from his old party to quit the caucus and help him start a new one, he told CBC News that since he announced his departure some 500 people have called him.

Another former leadership hopeful, Saskatchewan MP Brad Trost, is entangled in his own legal battle with the party over the membership lists.

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The Conservative Party determined that Trost's leadership campaign leaked a copy of the party's membership list to a firearms rights group and levied $50,000 fine against his campaign.

The Conservative Party uses a practice known as "salting" to trace leaks of its membership list. Each leadership campaign received a slightly different copy of the list to allow officials to trace back unauthorized releases.

Trost has insisted no one from his team was responsible and has threatened in the past to take his battle "all the way" to the Supreme Court.