Former Speaker of the House of Commons Baroness Boothroyd today called for urgent action over the "worsening structural condition" of the Palace of Westminster before "it is too late to prevent irreparable loss".
She is demanding a debate in the House of Lords to consider this crisis and "the threat to the iconic status as Britain's most famous World Heritage site".
A decision has already been drafted to place the Westminster site on Unesco's list of World Heritage Sites in Danger.
Unesco will debate it in Qatar next week, where attention will be focused on British accusations of football corruption over the World Cup.
The Westminster site, listed by Unesco for its "outstanding universal value". includes both Houses of Parliament, Westminster Abbey and St Margaret's Church.
Lady Boothroyd said today: "Speculation is rife about the worsening structural condition of both Houses of Parliament and there are strong concerns about the adverse visual impact of a growing number of high-rise buildings on this reach of the Thames.
"It's time the Government made clear its commitment to protect and preserve the Palace of Westminster as the heart of our democracy and a lasting symbol of our national heritage.
"English Heritage and Westminster City Council have made their objections known in court but the Government appears to be adamant. We need to examine this closely before it's too late to prevent irreparable loss."