MONTREAL -- The head of Quebec's biggest union has resigned, one day after an investigative report into his dealings with Premier Pauline Marois.

That report by Radio-Canada was just the latest difficulty to befall Michel Arsenault, chairman of the FTQ.

Quebec's corruption inquiry has been hearing wiretap testimony that includes Arsenault as the inquiry look at the union's ties to organized crime.

Arsenault says he's eager to tell his side of the story -- and defend the performance of the $9.3 billion union-investment fund that was allegedly targeted by mobsters.

"What a success story," Arsenault told reporters Monday.

"A $9.3 billion fund. Think about that. A fund that maintained or created 500,000 jobs in Quebec in the last 20 years. A fund whose value has increased the nine last semesters...

"We don't hear that (side) often."

He says his resignation has nothing to do with the revelations at the Charbonneau inquiry, and that at 63 years of age he's done his duty and wants to spend more time with his family.

He also denies that there was anything untoward about his dealings with Marois.

Radio-Canada reported that in 2008-09, he met with Marois twice just after the FTQ fund invested $3 million in a company part-owned by Marois's husband.

The network reported sources saying they doubted the value of the investment, which lost money, and believed it was being made to curry favour with Marois before she became premier.

None of those sources spoke on the record.

Marois denied raising her husband's project with Arsenault. And Arsenault, for his part, said he regularly meets with politicians to discuss a variety of topics.

"The head of the FTQ meets all politicians. The only politician who's ever refused to meet me, in six years, is Stephen Harper," Arsenault said.

The Harper government has announced plans to chop a federal tax credit for union venture-capital funds, which are especially popular in Quebec although their reputation has taken a hit at the Charbonneau inquiry.

As for Marois, she said she didn't raise her family business with Arsenault at those meetings -- or ever.

"I never talk about my husband's business with anyone," Marois said.

"He's old enough to speak for himself."

She said her millionaire husband's shares are held in a blind trust except for the company mentioned in the Radio-Canada report, the BLF investment trust.

She said that new business needed his experience but, at the appropriate time, she said her husband Claude Blanchet would treat it like all his other holdings.