Labour chairman Ian McCartney has indicated that Clare Short will not be expelled from the party over her United Nations bugging claims.
Ms Short says she has seen transcripts of calls to Mr Annan
He told BBC Scotland on Saturday: "I'm not going to make her a martyr".
She says Britain spied on UN Secretary General Kofi Annan, a claim Tony Blair has called "deeply irresponsible".
Meanwhile, the government has said it will not release Attorney General Lord Goldsmith's advice on the legality of the war in Iraq.
Both the environmental group, Greenpeace, and lawyers acting on behalf of the former intelligence officer turned whistle-blower Katharine Gun had asked to see the advice.
A Downing Street spokesman said: "The attorney general's advice remains confidential because of the long-standing convention that advice to governments in office is not disclosed."
In his BBC interview, Mr McCartney described Ms Short's behaviour in accusing the government of spying on the UN in the run up to the war in Iraq as "outrageous and unforgivable".
He accused her of having made "a terrible error of judgement" adding that she is "someone who has been totally, grossly irresponsible in what she has done".
Ms Short says she has seen transcripts of the UN leader's conversations, but Home Secretary David Blunkett said on Friday he had not, despite having access to more sensitive information.
Mr Blunkett said he would look into Clare Short's claims but criticised her for her "attempt to damage the government".
The ex-Cabinet minister continued to state the claims in a full front-page article written for Saturday's edition of The Independent.
She dismissed as "laughable" Tony Blair's accusation that her action had jeopardised national security.
Ms Short's former Cabinet colleagues have criticised her outburst as an attempt to undermine the prime minister.
But the expelled ex-Labour MP George Galloway defended her claims at the annual conference of the Stop The War Coalition in London on Saturday.
He said the past week would be looked back upon as "the week in which the beginning of the end of Tony Blair began."
"[Ms Short and Katharine Gun] have lit a fuse which is now burning all the way along Whitehall, all the way up Downing Street and is headed for Number 10," he said.
Galloway accused the government of 'lies and deception' over Iraq
The veteran Labour politician and anti-war campaigner Tony Benn also spoke at the conference.
He told attendees the "bugging story" had shown "that the American and British government hate the UN".
"Their real, long-term enemy is the UN, more even than Saddam," he said.
Former UN Secretary General Boutros Boutros-Ghali has said he was warned his office and home would be bugged while he was in office.
Richard Butler, the former UN chief weapons inspector, has also claimed at least four countries bugged his conversations and he is convinced the UN's headquarters in New York is full of spies.
UN chief spokesman Fred Eckhard said any bugging would be illegal and should be stopped.