OTTAWA, July 22 (Reuters) - Canadian Finance Minister Bill Morneau said on Wednesday he had repaid C$41,366 in travel expenses covered for him by a charity at the heart of an ethics probe and apologized for not doing so earlier, prompting new pressure from opposition legislators.

Morneau and Prime Minister Justin Trudeau face possible conflict-of-interest penalties over their ties with the WE Charity, which won a contract to run a C$900 million ($671 million) program to help students find work during the coronavirus outbreak.

Trudeau's brother and mother had both already received speaking fees from WE, which also employs one of Morneau's daughters. The affair is hurting the popularity of the ruling Liberals.

Morneau said he had written a check earlier in the day to cover the costs of expenses WE paid during private trips he and his family took to Kenya and Ecuador in 2017 to learn about the charity's projects.

Morneau said the matter was an oversight, insisting he had always intended to pay the full cost.

"Not doing so, even unknowingly, is not appropriate. I want to apologize for this error," he told the House of Commons finance committee.

The main opposition Conservative Party expressed disbelief and called on Morneau to resign.

"Do you expect us to believe that it is a mere coincidence that you repaid over C$41,000 ... on the same day you were expected to testify under oath about it?" asked Conservative legislator Pierre Poilievre. "You didn't know about a C$41,000 expense? How is that even possible?"

Trudeau and Morneau have both apologized for not recusing themselves during Cabinet discussions involving WE. The charity later walked away from the contract.

Morneau, 57, is a multimillionaire who has been finance minister since November 2015. He was fined by the ethics commissioner in 2017 for not declaring a French villa he owns.

($1=1.3411 Canadian dollars) (Reporting by David Ljunggren; Editing by Peter Cooney)