One of only three existing Enigma machines -- used by the Nazis to encrypt messages during the second world war -- has been stolen from the code-breaking museum at Bletchley Park in Buckinghamshire.
Bletchley Park was the location of Station X, the secret base at which Britain's top cryptanalysts broke the fiendishly complicated Enigma code used by the Germans to transmit war-time communications.
Identical Enigma machines, resembling typewriters, were used to encrypt and then decrypt Nazi communications and was for years considered unbreakable by Germany.
British mathematician Alan Turing was the principle code breaker at Bletchley who developed his own machines dubbed "Bombes" capable of deciphering the Enigma code. He contributed to the development of modern computational theory and technology.
The stolen machine was brought to the Bletchley museum following the war and is believed to be worth around £100,000.
In a statement, director of the Bletchley Park Trust Christine Large commented, "This is a selfish act, calculated to deprive the visitors and students at Bletchley Park of the chance to enjoy and appreciate a unique piece of history."
Although security has now been upgraded at the museum, Large added, "The Trust will be deeply grateful for any information that may lead to the return of the machine."
Security firm Polaris Telemetry has agreed to sponsor the installation of a new high-tech surveillance system at the museum.
Bletchley Park Telephone number is 01908 640404