Chancellor Gordon Brown has urged people to wait for the "full facts" of the police investigation into cash-for-honours allegations to emerge.
His comments came as Downing Street once more insisted that it had "fully co-operated" with the police inquiry.
The re-arrest on Tuesday of Prime Minister Tony Blair's fundraiser Lord Levy on suspicion of conspiracy to pervert the course of justice sparked speculation that the Metropolitan Police team led by Deputy Assistant Commissioner John Yates are now focusing on a possible cover-up of the sale of honours.
Reports have suggested that officers are investigating the possibility that messages relevant to the inquiry were sent on an email network separate from the main Number 10 system and then deleted.
But Mr Blair's official spokesman on Wednesday repeated that people working within 10 Downing Street do not have access to alternative email networks, for security reasons.
And he told reporters at a regular daily briefing: "We have co-operated at all times with the police and we have fully co-operated at all times with the police...
"There is only one system. The police have had full access to that system and we have had no complaints otherwise."
On BBC Scotland, the Chancellor was asked whether he feared that there may have been some kind of cover-up in Number 10, and replied: "I believe when people see the full facts then they will be satisfied."
It would be inappropriate for him to comment on Lord Levy's arrest while the inquiry continued, he said.
Mr Blair's spokesman confirmed that Lord Levy remained the PM's Middle East envoy.
