New environment secretary David Miliband has been linked to a nuclear industry lobbyist.
The lobbyist in question is Alan Donnelly, chair of Mr Miliband's local constituency party, according to the Sunday Times.
Mr Donnelly is alleged to have paid for the refurbishment of the minister's constituency party headquarters in Newcastle.
The Sunday Times says it has documents showing that Mr Donnelly's lobbying firm, Sovereign Strategy, paid £2,000 in building works for a terraced house in South Shields, Tyneside.
Mr Miliband has reportedly not declared the payment in the register of members' interests.
Sovereign Strategy represents the US multinational company Fluor, a global nuclear firm.
It is preparing to bid for a stake in the £70 billion UK nuclear waste market, the newspaper claims.
Former Labour MEP Donnelly also set up the Transatlantic Nuclear Energy Forum (Tanef), a body that seeks to form "strong relationships" between nuclear power firms and governments.
Conservative environment spokesman Peter Ainsworth said: "The question of our future energy supply is crucial and we can't have these decisions made on the basis of hidden links to the nuclear industry or lobbying activities.
"The whole process should be unbiased."
His Liberal Democrat counterpart Chris Huhne said: "It is worrying if there are clear links between Miliband and a prominent nuclear lobbyist as it calls into question his impartiality."