John Prescott denied any wrongdoing last night after a fellow Minister revealed he was involved in decisions over super-casinos while a US billionaire was bidding to build one at the Dome.
Culture Secretary Tessa Jowell said she remembered holding talks with Mr Prescott at the end of 2004 on how many casino sites should be approved.
But a spokesman for the Deputy Prime Minister said there had been a single, brief and "entirely legitimate" discussion about casinos' regeneration potential.
Numbers and location had not been mentioned in the exchange, the spokesman insisted.
Giving evidence to the Culture, Media and Sport Select Committee, Ms Jowell said she could "recall conversations with the DPM about the number of regional casinos".
The Deputy Prime Minister has faced growing criticism over recent weeks concerning his contacts with billionaire Philip Anschutz, who bought the Dome in 2002.
He has admitted meeting Mr Anschutz seven times since August that year, and was rebuked by Commons watchdogs last week for failing to declare a visit to his Colorado ranch until it emerged in the press.
Mr Prescott was in charge of planning and regeneration of the Dome up until the Cabinet reshuffle in May. But he has repeatedly denied having anything to do with casino licences, and says he left Dome planning issues in the hands of officials.
Ms Jowell told MPs: "If I cast back, I can certainly recall conversations with the DPM about the number of regional casinos that would be consistent with the regeneration objective.
"But this was very much in terms of the development of the policy statement on casinos (released in December 2004)."
Asked whether Mr Prescott had pushed for more sites to be approved, she replied: "Any discussion that I had with the DPM was in the context of the development of the statement of policy on casinos."