Transport Minister Julie Boulet says she made a mistake by saying it was legal for companies to make political donations in Quebec. (CBC)

Quebec's Transport Minister Julie Boulet is denying she is at the centre of an investigation into Liberal Party fundraising in her Mauricie-area riding.

A review of the Laviolette riding office's financial report raised enough questions to warrant a formal investigation, officials said on Wednesday.

The review was launched following comments made by Boulet in the national assembly in February about alleged cases of favouritism in the awarding of contracts by the Transport Ministry.

In fact, since 1977, companies have been barred from making political donations. Only individuals on the electoral list can make political contributions — and only a maximum of $3,000 a year. They cannot be reimbursed by a company for making a donation on its behalf.

The comment was just a mistake, Boulet told reporters in a news conference at the national assembly on Wednesday.

She said she had been assured by the office of the chief electoral officer that its investigation was not related to her or her riding association.

"Is there a donor that could have been reimbursed by their company? I don't know," said Boulet.

Transport, education ministers face reviews

The office of the chief electoral officer is also continuing reviews of the actions of Education Minister Michelle Courchesne and junior transport minister Norman MacMillan, who suggested last fall that companies were permitted to make political donations.

In the case of the education minister, the investigation has been slowed by the fact that officials have been unable to reach her official agent, Benoît Cyr, who is responsible for Courchesne's fundraising. As a result, officials will have to visit Courchesne's riding office in person.

'Three mistakes in a row — I think that is enough,'—PQ Leader Pauline Marois

The three ministers should be suspended pending the results of the investigations, said opposition Parti Québecois Leader Pauline Marois, who accused the Liberal Party of trying to sweep the problems under the rug.

"Three mistakes in row — I think that is enough," said Marois.

Officials are also probing whether donations made to the Liberal Party of Quebec by 20 employees or managers of engineering firms CIMA+, AXOR, BPR and SNC-Lavalin were made legally, following questions raised by Québec Solidaire MNA Amir Khadir.

Khadir presented chief electoral officer Marcel Blanchet with a list containing the names of 123 donors who contributed a total of $300,000 to the Liberals.

On Wednesday, he told reporters the list contains some unlikely donors that raises questions about whether contributors were donating on behalf of themselves or corporations.

"There is a question to ask: why a secretary or a technician would give $3,000 to the Liberal Party?" said Khadir.

A letter from the chief electoral officer was sent to each of the individuals asking them to confirm whether their donation conformed with the province's laws.

The 23 people who are the subject of the investigation have so far failed to respond to the letter.

With files from The Canadian Press