Federal authorities will look into Victorian opposition leader Matthew Guy’s lobster with an alleged mobster scandal, which has claimed a Liberal party scalp.

Guy spent a second day on Wednesday batting away allegations his April dinner meeting at Melbourne’s lavish Lobster Cave restaurant was a cover to procure a political donation. And then Canberra intervened.

“Those reports will be carefully examined by federal authorities,” the prime minister, Malcolm Turnbull, told parliament.

His statement came in response to a question from Labor about whether the Australian federal police have been asked to investigate the latest turmoil in Victorian politics.

Guy has already referred the matter himself to the Independent Broad-based Anti-corruption Commission. He insists he met with long-time Liberal supporter Frank Lamattina and his cousin, the alleged Melbourne mafia boss Tony Madafferi, to discuss the fruit and vegetable markets.

The Liberal leader also says he did not know Madafferi would be at the dinner until he arrived, political donations were never discussed and none have been received since.

But recordings obtained by Fairfax quote the Liberal party figure Barrie MacMillan suggesting the dinner was to solicit donations and Guy’s office was told of Madafferi’s presence.

“You can’t associate Matthew with money, and I would have to be the intermediary, but I’m talking about a swag of money that they’re prepared to give,” MacMillan is heard saying.

On Wednesday morning Guy called for MacMillan to “move on” and by late afternoon the electorate conference secretary for the federal seat of Dunkley had quit.

“I have today accepted Mr Barrie MacMillan’s resignation,” state director Simon Frost said in a statement.

The scandal has “Labor’s dirty hand” all over it, the Victorian Liberal party president, Michael Kroger, said on Wednesday.

But the premier, Daniel Andrews, rejected any suggestion of involvement by his party.

“That’s just a complete nonsense, a complete and utter nonsense,” he told reporters.

Andrews seized the opportunity to condemn Guy for “taking the mafia’s money” when the opposition tried to continue its “tough on crime” agenda during question time.

On Wednesday afternoon parliament debated whether the Liberals were financially and morally “bankrupt”.