Progressive Conservative member Chris d'Entremont said Economic Development Minister Michel Samson withheld the fact that the province had spent an additional $2.5 million on the Nova Star ferry when he was asked about the cost of the service last Thursday.
Samson has since confirmed he has known about the additional spending since Dec. 23.
"To me, that's a lie," d'Entremont said. "If you're going to stand there and stretch the truth or lie, I don't think that's the right way to conduct a government."
Earlier in the day, Samson said he had made a mistake when responding to reporters' questions last week.
"Last Thursday, when I was asked the question of the total amount, I misspoke," he said. "If I could go back, I would do it differently. It was always our intention ... of making sure that Nova Scotians had all of the information in front of them."
But the minister later altered his explanation. He said he had planned to disclose the spending but not until he could make a "package announcement" that included good news about the ferry's pending operating schedule for this year.
"We were under the honest belief that a deal was mere days away," he said.
But that good news has failed to materialize and Samson did not reveal the information until last Sunday when he issued an unrelated statement about a snafu with an audit of the ferry's costs.
Samson has been out of the province since then. He responded to reporters' questions Thursday during a conference call from Orlando, Fla., where he is promoting Cape Breton as a golf destination.
He said no announcement was made when the spending decision was made Dec. 23 because "people would be on holidays and not necessarily following such an update."
When asked about the new costs for the ferry, Premier Stephen McNeil said the file was Samson's responsibility.
The province's taxpayers have now spent $28.5 million for the service, which includes a $21-million loan that was spent in the first two months of the inaugural sailing season. That loan that was supposed to last seven years.
"This government was supposed to be open and transparent and it's anything but," said NDP house leader Frank Corbett.
"At one point, the minister said he misspoke, then the next minute he's saying, 'I was going to give it to you as a package.' Which one is it?"
The province's previous NDP government promised to revive the service after killing it in 2009 by eliminating an annual subsidy. That subsidy totalled $15.7 million over the last four years that the ferry service was in operation.
Nova Star Cruises has said the ferry is headed to Charleston, S.C., where it would berth for the immediate future or until winter work is found.
Follow @NovaMac on Twitter.