The historic site of Britain's crucial code-breaking programme during the second world war is so shabby it has become a "national disgrace", scientists warned today.

Bletchley Park, which helped launch the modern computer, is in a "terrible state of disrepair" because of a lack of investment, say professors and heads of science from universities across the country in a letter to the Times.

"As a nation we cannot allow this crucial and unique piece of British and world heritage to be neglected," the 97 signatories say.

"The site, buildings, resources and equipment at Bletchley Park must be preserved for future generations."

They call for the house and its surrounds, in Milton Keynes, to be made into a national museum of computing.

Bletchley Park is open to the public as a museum but receives no public funds. The Prince of Wales is due to meet veteran codebreakers there today.

Dr Sue Black, head of computer science at the University of Westminster, told the BBC: "I went up there and felt quite upset by what I saw… [it was] a national disgrace."

The Times letter says: "Although there has recently been some progress in generating income, without fundamental support Bletchley Park is still under threat, this time from the ravages of age and a lack of investment.

"Many of the huts where the codebreaking occurred are in a terrible state of disrepair."

Bletchley, a Victorian mansion, played a fundamental role in winning the war. The Government Code and Cipher School arrived there in 1939 and its mathematicians managed to crack the complex Enigma codes, which the Germans thought were unbreakable.

After the war was won, Winston Churchill, who told workers they were the "geese that laid the golden egg", destroyed all evidence of the codebreaking programme.

By the end of the war, 63m characters of high-grade German messages had been decrypted by the 550 people working on the Colossus machines at Bletchley Park.

Workers were sworn to secrecy but, in 2006, Colossus was put back together using eight photographs of the machine taken in 1945, as well as circuit diagrams that were kept illegally by engineers who worked on the original project.

Authors of the letter include Prof Bill Roscoe, director of Oxford University's computing laboratory, and his Cambridge counterpart Prof Jean Bacon; Prof Ian Sommerville, of the University of St Andrews; and Prof Robert Churchouse of Cardiff University.