George Osborne is facing suggestions he has "something to hide" after failing to publish details of guests entertained at his grace-and-favour country home.
The Chancellor enjoys the use of imposing 18th century Dorneywood in Buckinghamshire, as well as his apartment in Downing Street.
He reportedly held a party for his 40th birthday there, and it emerged during the Leveson Inquiry that he invited former News International chief executive Rebekah Brooks and her husband to stay for a weekend in 2010.
But while the Prime Minister, his deputy Nick Clegg and the Foreign Secretary have disclosed lists of whom they have entertained at Chequers and Chevening, Mr Osborne has yet to follow suit.
The omission comes despite then-Treasury minister Justine Greening promising in a reply to a parliamentary question in 2011 that a list would be published "in the usual way".
But in response to Freedom of Information requests, the department has insisted that it does not hold the details as the residence is for "private use".
A spokesman said: "The Prime Minister offered the house to the Chancellor of the Exchequer on his appointment for his private use.
"Accordingly the Treasury does not hold details of who has been entertained there."
The response stressed that Mr Osborne did publish quarterly details of his ministerial meetings.
Alongside releasing a list of his Chequers guests, David Cameron has previously been forced to reveal dinners and lunches with Tory donors at the residence and in Downing Street even when the taxpayer did not foot the bill.
Dorneywood was gifted to the nation in 1942 as a bolt-hole for senior ministers. It is owned by the National Trust and the upkeep is paid for by a charitable trust.
Labour MP John Mann said the fact Mr Osborne had not published a list was "outrageous".
"This is not his property. It is the taxpayer who is funding these visits," he said.
"People are entitled to know who is there and what it is costing them.
"It is begging the question of what have they got to hide?"