Opposition Leader Jess Wilson lobbed the schools funding accusation in a letter to the state's treasury secretary on Wednesday.
The letter does not state how significant those cuts would be but linked the cuts to a decision reached internally by Labor in October.
It comes as Victoria's Department of Treasury and Finance prepares to release its final pre-election budget health check on Thursday.
Ms Wilson urged the secretary to include any funding cuts in that update.
"Victorians are entitled to know the decisions being made in their name," she wrote in the letter shared with AAP.
"We also ask that you also disclose in the (budget update) any other secret cuts or taxes that the Andrews-Allan-Carroll Labor Government has failed to tell the Victorian people about."
Labor has denied making any cuts, claiming the funding decision was taken to ensure private schools do not exceed their entitlements under the Schooling Resource Standard.
The joint federal and state standard sets out how much public funding schools need to meet students' needs.
"Catholic schools will never have their funding cut under Labor," a spokesperson told AAP.
The row opens a fresh line of attack weeks out from Victoria's November 28 state election.
The Liberal Party will be without a candidate for the inner-city electorate of Williamstown, after disendorsing Paul Lindemann from the post on Wednesday.
The party reached the decision after becoming aware of a series of "offensive" online comments about Indigenous Australians.
Ms Wilson said it was "disappointing" the posts had not been identified during the vetting process, but insisted the party acted swiftly once they were brought to its attention.
"Those comments that the candidate made were deeply offensive," she told ABC News Breakfast on Thursday.
The Liberal leader will spend the day campaigning on health, after announcing a $20 million funding pledge for children's health research.
It will support the Murdoch Children's Research Institute's Generation Victoria program, which aims to improve early diagnosis, prevention and intervention for children's health.
"Every parent wants their child to have the best possible start in life," Ms Wilson said.
Both parties have made a series of health-related pledges in recent weeks, including Labor's pledge to boost free dental clinics statewide.
Meanwhile, Premier Ben Carroll will unveil a $420 million investment in regional train services, designed to expand the state's V/Line fleet.
More than 550 services will be added across every train line, with the Melton Line, which goes to Melbourne's outer northwest, set to gain an additional 162 services from 2027.
"Now we can realise the benefits of Labor's upgrades: delivering more train services and giving you a more reliable way to get around," Mr Carroll said.
The coalition in September pledged to back greater train capacity and deliver more trains across the state.
Under the plan, the party said they would introduce new hybrid electric trains on the Melton and Wyndham Vale lines to free up 25 three car set V/Line trains.
