Quebec Transport Minister Jacques Daoust quit politics on Friday just hours after Premier Philippe Couillard indicated he no longer had full confidence in the minister.

Daoust, 68, had faced mounting criticism in recent months over his alleged role in authorizing the sale of a Quebec hardware chain to American giant Lowe's while he was the province's economy minister.

Although Daoust maintained he didn't know about Investissement Quebec's decision to sell its shares in Rona, emails sent in 2014 and obtained by TVA suggested the vice-president of the provincial investment agency had been given the go-ahead from Daoust's former chief of staff.

Members of the opposition had called for Daoust's resignation, accusing him of having lied to the public.

When asked earlier Friday if Daoust still had his confidence, Couillard said he wanted answers to the "serious questions" that had been raised about the Rona sale.

"Serious questions have been asked," he said. "They are important to me and they need to be answered very quickly."

Daoust was appointed transport minister in January.

In a statement announcing his resignation, Daoust maintained he never knew about the Rona sale but didn't want to be a distraction to the government.

"It's clear that, although I have...always told the absolute truth, the file that concerns the Rona shares has become a distraction that overshadows the fulfilment of our government's plan," he wrote.