David Clark, Chancellor of the Duchy of Lancaster, made the comment after newspaper stories appeared about the pounds 50,000 cost of three fact-finding visits to the US, Canada, and Australia to compare international freedom of information laws.
Dr Clark was said to have upset his officials by travelling first class while they went club class.
Another report referred to the minister having lost some of his baggage on one trip - information which could only have been known to a few officials.
During the summer the minister was the object of criticism over delays to the Freedom of Information Bill, which he blamed on the civil service. Some reports have tipped him as a possible victim in a Cabinet reshuffle.
Dr Clark said: "I don't think there's any doubt that there is somebody running a smear campaign against me. The media has considerable detail, basically much of it true. Somebody somewhere is digging out information and giving it to the press."
Later he said he did not believe a fellow minister was behind the campaign. That ruled out the possibility that Dr Clark was identifying Peter Mandelson, a minister of state in his department, as the culprit.
One source said: "He has a very good relationship with his civil servants, but civil servants would be the first to accept that official information should not be used or abused in any way which can be seen to undermine his work."
The Conservatives seized on the row, arguing that Dr Clark was a victim of the "culture of briefing and counter-briefing which surrounds and pervades this government".
Gillian Shephard, Shadow Chancellor of the Duchy of Lancaster, said: "David Clark is claiming that he is the victim of his own government's leaking.
"Dr Clark should account for these trips and immediately ask the Prime Minister to order a leak inquiry which should cover all those with access to this type of information, including Mr Blair's own staff."