He wants longer jail sentences and the removal of a key legal defence of “necessity” for whistleblowers.

The crackdown is aimed at preventing cases such as that of Katharine Gun, a former translator at GCHQ, the government’s eavesdropping centre, who leaked a memo showing that in the months before the Iraq war in 2003 the Americans wanted GCHQ’s help in bugging the homes and offices of UN security council members.

The government dropped its case against her after she threatened to use the necessity defence that she broke the law to prevent a greater “crime” in the form of an invasion of Iraq.

Ministers are also concerned at the growing number of leaks of sensitive documents by dissident officials, including those relating to the MI5 investigation into the July 7 bombings.

It will be the first change to the official secrets legislation since 1989 when the government removed the right of whistleblowers to claim a defence of public interest.

Reid wants the bill to be included in this autumn’s Queen’s Speech so it can be brought into law during the next session of parliament.

The proposals could see the present maximum of two years in prison in the 1989 Official Secrets Act doubled to four.

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