Disgraced US lobbyist Jack Abramoff had more extensive contacts with the White House than previously admitted, a Congressional inquiry has reported.
Mr Abramoff has pleaded guilty to conspiracy to bribe public officials
Mr Abramoff and his associates made contact with White House staff more than 480 times between 2001 and 2004, the inquiry found.
But administration officials say the report is based on records that are "widely regarded as fraudulent".
Mr Abramoff has admitted conspiracy to bribe public officials.
Correspondents say that while the report suggests no impropriety on the part of the Bush administration, it could still be used by the Democrats to try to embarrass the White House in the run-up to Congressional elections in November.
They say it will allow Democrats to renew their charges of a "culture of corruption" against the administration.
The report alleges that Mr Abramoff purchased expensive gifts and dinners for some White House officials and other Republicans in attempts to gain their influence for his clients.
It is not clear whether these broke rules on lobbying.
Of 485 contacts listed in the report, 345 are described as meetings or other in-person contacts; 71 were telephone conversations and 69 were e-mail exchanges, the report says.
But it says that in many cases Mr Abramoff did not get the results he was seeking.
President George W Bush's top political adviser Karl Rove was among Mr Abramoff's lobbying targets, the House Government Reform Committee report says.
The White House has challenged the credibility of the report, which draws on 14,000 pages of e-mails and billing records spanning three years ending in 2003.
"The billing records that are the basis for this report are widely regarded as fraudulent in how they misrepresent Abramoff's activities and level of access," said deputy White House press secretary Dana Perino.
"There is no reason why they should suddenly be viewed as credible."
Some of the contacts in the records could not be verified by the committee, the report said, according to the Associated Press news agency.
In his plea agreement, Mr Abramoff has admitted he defrauded clients.