UPDATE: Insults fly between Legault and Couillard on Day 18 of Quebec campaign

Insults flew between candidates on the Quebec campaign trail on Sunday as verbal sparring between CAQ leader Francois Legault and Liberal counterpart Philippe Couillard overshadowed announcements on health care, culture and environmental protection.

Couillard accused the Coalition Avenir Quebec's leader of having created a financial plan based on "hypothesis'' rather than fact, while Legault shot back by comparing Couillard to Santa Claus and said his policies resembled those of left-wing party Quebec solidaire.

The exchange began with Couillard, who criticized Legault's financial plan, which promises to boost health and education spending without raising taxes beyond the level of inflation.

"When there are commitments that literally disappear from the financial framework, that are massively underestimated, we're beyond hypothesis, we are in error,'' Couillard said in Trois-Rivieres, halfway between Montreal and Quebec City.

Almost 200 kilometres away in Lac-Megantic, Legault criticised his Liberal party rival's "ridiculous'' number of big budget promises.

"When we look at all the expenses that have been announced in the last six months, they're getting closer to Quebec solidaire, and they're not doing much to put money back in Quebecers pockets,'' said Legault, who said his rival's spending earned him the moniker "Santa Claus Couillard.''

One of Quebec solidaire's co-spokespeople, however, reacted with humour to Legault's claim that the Liberal party's policies resemble those of her party.

"Our ideas are so popular, it's normal they're trying to copy us!'' Manon Masse wrote on social media.

While their verbal exchanges drew attention, the leaders also unrolled a series of promises in the area of health, culture and consumer protection.

Parti Quebecois Leader Jean-Francois Lisee promised to tackle high gas prices through his planned Quebec consumer protection office, which he said would look into price fixing by "gas cartels.''

"Every Tuesday or Wednesday, something wrong happens in the gas stations in the Montreal area,'' he said, referring to predictable early-week price hikes.

"This situation just begs for an inquiry, so that's why it's going to be the first (file),'' he said.

Couillard, for his part, pledged to help the province's 1.5 million caregivers by creating a tax credit of up to $2,400 per year to help them renovate their homes to accomodate an elderly person.

Couillard also promised to implement a governmental action plan to help caregivers which would include the development of different respite services for patients.

He estimated his promises will cost $60 million, $40 million of which would be for the credit.

Legault, meanwhile, promised to increase funding to libraries and offer two cultural outings a year to elementary and high-school aged children.

Quebec solidaire focused on environment and agriculture, promising to redirect funds from a trust to pay down public debt to instead be used to tackle climate change and finance green infrastructure.

Speaking in Quebec's Eastern Townships, Masse also unrolled an agricultural plan that would boost subsidies to organic producers, support local supplies, and review rules governing pesticide use.