Nathalie Normandeau, former second-in-command in the Quebec Liberal government of Jean Charest, was among seven people arrested Thursday as part of a sweep by the province's anti-corruption unit, UPAC.

The multiple arrests targeted members of the Quebec Liberal Party and the Parti Québécois and are related to illegal campaign financing.

"These offences are serious not only because they're against the law, but because they threaten the principles of democracy and the sound management of public funds," Robert Lafrenière, the head of UPAC, said at a news conference.

"It is unjust and unfair to use public contracts as a political tool."

The arrests came just hours before Quebec's Liberal government released its 2016 budget.

Normandeau, who was Quebec's deputy premier under Jean Charest from 2007 to 2011, faces charges that include conspiracy, corruption, breach of trust and bribery in relation to the awarding of a contract to build a water-treatment plant in Boisbriand, Que.

The charges come with a maximum sentence of 12 years.

Marc-Yvan Côté is a former Liberal cabinet minister and vice-president of the engineering firm Roche. (National Assembly) wouldn't confirm at the news conference that the charges relate to the Boisbriand water contract, but sources indicated to Radio-Canada that was the case. UPACBoisbriand

According to public documents, Normandeau, who was municipal affairs minister at the time, overruled senior bureaucrats to award the $11-million contract to engineering firm Roche.

Roche also did fundraising for Normandeau during her time as an MNA and Liberal candidate.

Normandeau's name came up frequently at the Charbonneau Commission, the province's corruption inquiry.

Her lawyer, Maxime Roy, said investigators arrived at her home early Thursday morning with an arrest warrant.

"We were surprised by the charges," Roy said. "She has done nothing wrong and we intend to show that."

He added that Normandeau intends to plead not guilty to the charges.

Marc-Yvan Côté, a former Liberal cabinet minister under premier Robert Bourassa and vice-president of the engineering firm Roche, and Bruno Lortie, Normandeau's former chief of staff, were also arrested this morning.

Côté was also a campaign organizer for the federal Liberals, and was kicked out of the party by former prime minister Paul Martin over the sponsorship scandal.

France Michaud, another former vice-president of Roche and Mario Martel, a former chief executive officer at the same, were also arrested.

'We've completely changed': Couillard

The arrests represent a blow to the Quebec Liberals, who were dogged by allegations of corruption under Charest.

Quebec Premier Philippe Couillard addressed the arrests ahead of Thursday's provincial budget. (CBC) Premier Philippe Couillard told reporters in Quebec City the Liberal Party has taken steps in recent years to crack down on illegal fundraising.

"We've completely changed the way we do things because of laws, because also the way we've done things internally, creating a code of ethics," Couillard told reporters in Quebec City.

"Since we've dropped, on top of other measures, the [donation] limit to $100 per person per year, I can tell you the ambience is totally different. Fundraising is not an issue for us."

PQ also implicated

Two people with ties to the Parti Québécois were arrested, including François Roussy, the former mayor of Gaspé and a staffer for PQ MNA Gaétan Lelièvre.

Ernest Murray, an ex-attaché in the riding office of Pauline Marois, was arrested too.

Prosecutors laid charges against Roche earlier this week. The firm has been the target of UPAC raids.