John Prescott's involvement in the allocation of 'supercasino' licenses has been called into question by the Conservatives.

The deputy prime minister has been the subject of press reports over the weekend concerning his one-night stay last year at the US estate of US tycoon Philip Anschutz.

Anschutz is the owner of AEG Entertainment, which was handed the lease of the Millennium Dome in 2004 in return for a share of future profits from its use as an entertainment complex.

Prescott has denied there was any conflict of interest between his ministerial role and his relationship with Anschutz, although at the time of his visit he had ultimate ministerial responsibility for the regeneration of the dome.

The dome is also one of eight locations on a shortlist of possible sites for Britain's first 'supercasino'.

The deputy prime minister's former department oversaw planning policy for casinos, although the location of the first 'supercasino' will be judged by an independent panel which is the responsibility of the Department of Culture, Media and Sport.

Speaking during culture questions in the Commons on Monday, shadow minister Hugo Swire said the process for awarding regional casino licenses was "mired in chaos, confusion and disarray".

Dismissing Swire's statement as a "load of rubbish", culture minister Richard Caborn said the independent panel was a "transparent system" at arms-length from the government and the DCMS.

But Swire said: "Does the minister in his own words consider it transparent and at arms length that senior government ministers are being entertained on the estates of American casino operators?"

"Will he act urgently to ensure complete and full disclosure of the facts to ensure public confidence and transparency in the process?"

Caborn said his comments were "absolutely disgraceful".

"The deputy prime minister... had no role in planning, had no role in negotiations, and has had no role in the siting of casinos.

"It's totally untrue and unfounded and the only thing that's been brought into disrepute is the member opposite."

The Tories have called for the parliamentary commissioner for standards to investigate Prescott's trip.