A company run by the boss of the firm proposing a tidal lagoon for Swansea offered to set up a community fund in Cornwall if a parish council did not object to the reopening of a quarry.
Tidal Lagoon Power chief executive Mark Shorrock denied to MPs that the company made a financial inducement.
But a draft agreement seen by the BBC suggests Shire Oak Quarries proposed a community fund linked to rock exports.
Mr Shorrock said he was denying improper behaviour.
According to official documents at Companies House, Mr Shorrock has "significant control" of Shire Oak Quarries.
The agreement, which is dated 2015, proposed that the council would give "reasonable support" to the application for planning permission to reopen Dean Quarry - "and not make representations against such application".
It stated: "Shire Oak may terminate this agreement at its absolute discretion if the parish council is in breach of this clause."
St Keverne parish councillors refused to sign the agreement, according to the council clerk.
MPs on the Welsh affairs and business and energy select committees have now written to Mr Shorrock asking him to clarify his evidence to them at a hearing last week.
Mr Shorrock told the MPs he bought the quarry because he did not want to be "hidebound" to large quarries in Norway.
Keith Clarke, the chair of Tidal Lagoon (Swansea Bay) plc - a subsidiary company owned by Tidal Lagoon Power - has now written to the chairs of the committees suggesting that it is unlikely Dean Quarry could be used for the lagoon.
In a statement issued on Tuesday, he said: "The Board of Tidal Lagoon (Swansea Bay) Plc determined some time ago to deal with the potential conflict of interest arising from Mark Shorrock's personal interest in Dean Quarry. The company itself has no interest in Dean Quarry nor any involvement in the commercial activity of Shire Oak Quarries Ltd.
"Following last week's meeting, the Board has written to the select committee chairs to restate its position on where and how rock for its project will be sourced. We trust there is now complete clarity on a matter the Board considers has distracted unnecessarily from a project of vital importance to the UK's future portfolio of home-grown, reliable, low carbon, low cost power".
In last week's hearing, Mr Shorrock denied that he encouraged the council to accept a financial inducement to support the planning application.
Conservative MP David Davies, who chairs the Welsh Affairs Committee, asked him: "Some campaigners in Cornwall have suggested that, in order to get planning permission through, you encouraged a parish council to accept a financial inducement in order to support the planning application right the way through. Is there any truth in that allegation?"
Mr Shorrock initially replied: "If you are talking about the quarry in Cornwall, it has full planning permission."
Mr Davies added: "Is there any truth in the allegation that your company offered a financial inducement to the parish council?"
Mr Shorrock: "No."
Mr Davies: "That is great. We can put that to bed. You are on the record now as having said no to that."
Mr Shorrock: "I have just said no."
On Wednesday, Mr Shorrock told the BBC that he felt that the use of the word "allegation" by the committee chair implied impropriety, which is what he was denying.