Senior mason Lord Farnham branded the move ''offensive, arbitrary, oppressive and without justification''.

In a curt letter to Home Secretary Jack Straw, Lord Farnham, Pro Grand Master of the United Grand Lodge, said the masons would only hand over the names if forced by law.

Myth and legend surround many of the secret rituals

Lord Farnham said the request went against the principles of the right to privacy and freedom of association.

Under proposals initiated by Mr Straw, the government is asking judges, magistrates. police officers, prison and probation officers and Crown Prosecution Service lawyers to voluntarily declare if they are masons.

The responses would be published in a public register in order to introduce greater openness into the criminal justice system.

The government has said if the masons do not comply with the request it may pass new laws enforcing it.

But Lord Farnham said: "To confine the proposals to freemasons is highly discriminatory, likely to encourage discrimination against freemasons by others and to entrench discrimination in many other spheres as acceptable behaviour.

"To single out a section of society for special treatment of this nature is a dangerous path not in accordance with our understanding of democracy.''

Britain has about one million freemasons, many of whom are associated with the police, legal profession and local governments.

Lord Farnham said there was no evidence "even tending to show that freemasons in general have perverted the course of justice".