Buckingham Palace is one of the buildings in need of repair
Buckingham Palace should open to the public more often than the current 63 days a year in order to raise much-needed funds, a group of MPs has said.
But the Keeper of the Privy Purse said access had to be restricted because the Palace was so frequently occupied by the Royal Family and other dignitaries.
The Public Accounts Committee (PAC) is questioning senior royal officials about the state of Britain's palaces.
There is currently a £32m backlog of maintenance work due to be carried out.
The PAC said the White House in Washington DC was open to tourists for much of the year and suggested that Buckingham Palace could also be more flexible about its visitor policy.
In response, Keeper of the Privy Purse Sir Alan Reid said members of the Royal Family were in residence at the Palace for about 300 days of the year.
He said the Queen regularly held audiences there three or four times a week, as well as investitures on 22 days of the year and more than 100 receptions.
But PAC chairman Edward Leigh replied: "You cannot close the whole palace because the Duke of York is sitting in his flat upstairs."
Sir Alan said he did not believe it was appropriate for the public to be allowed access during visits to the Palace by foreign heads of state.
And he pointed out that tourists could visit Windsor Castle on about 360 days of the year.
Windsor Castle is open for about 360 days each year
Royal officials said opening Buckingham Palace more often was not financially viable because of the increased staff and administration costs that would result.
But the committee questioned this, arguing that it would be easy to find relatively low cost, casual workers among London's large student population.
Last month, a National Audit Office report highlighted the huge maintenance backlog at Britain's occupied royal residences.
It said the Department for Culture Media and Sport - ultimately responsible for their upkeep - and the Royal Household had not agreed a way of managing the repairs.
The report also said there was no clear system for monitoring whether the palaces were being maintained to a standard consistent with their architectural and historic status.