Because the project sought more than $1 million, approval had to be signed off by Finance Minister Grant Robertson, Transport Minister Phil Twyford and Economic Development Minister David Parker, who attended the meeting along with Jones.
According to MBIE senior advisor Mark Patterson, Jones gave assurances to Robertson about the project's viability.
"Minister Robertson raised his concerns about the broader management and commercial operations of the project," Patterson's email about the meeting said.
"Minister Jones provided reassurance that as the project has Far North Holding Ltd, the commercial arm of the Far North District Council, involved in its governance structures, he was comfortable their presence would alleviate any concerns on the issue.
"Minister Robertson was comfortable to sign the briefing knowing this mitigation was in place."
Tourism Minister Kelvin Davis announced the funding for Manea on February 23.
Two months later, in answer to a written parliamentary question, Jones said he had had "no formal meetings regarding the Manea Footprints of Kupe project since receiving my ministerial warrants".
Seymour said Jones' reassurances about Manea at the meeting were out of line, given the conflict of interest, and he was not fit to be a minister.
He added that Jones had concealed his presence at the ministerial meeting in his answer to the parliamentary question.
"Given he was to be the project's chairman, Shane Jones has a clear conflict of interest in relation to Manea. It is deeply concerning that he would intervene when it was completely inappropriate for him to do so," Seymour said.
"The Minister's misleading answer to a parliamentary question when asked if he had attended a meeting about the Manea project shows he is not fit for ministerial office.
"The Prime Minister has no choice but to sack him."
The Cabinet Manual says that a minister has to declare conflicts of interests, and affected issues can be transferred to another minister.
The minister also needed to consider whether it was appropriate to be present at Cabinet or Cabinet committee meetings that discuss issues involving the conflict of interest.
Jones has said he transferred responsibility for decisions about Manea to other ministers.
He told Stuff he did not advocate for Manea during the February 12 meeting, but instead offered "statements of fact" about the involvement of Far North Holding Ltd.
He believed he had managed the conflict of interest appropriately, despite being present at the ministerial meeting, where he said Kelvin Davis voted in his place.
Jones told Stuff he was never going to chair Manea, and any such suggestion was just "wishful thinking" by Manea.
The Manea project is to build an all-weather centre, creating 17 full-time jobs, about the legend of Kupe. It had been turned down for funding by the previous government.
National Party regional development spokesman Paul Goldsmith said Jones needed to explain why he was reassuring ministers about the governance of the project.
"The Prime Minister should haul him into the office and get him to reconcile what appear to be irreconcilable statements: that he wasn't involved, and that he was at the meeting and seems to have been very active.
"On the surface of it, it's not a good look, and not the way we do things."
The Prime Minister's office has been approached for comment.
