Opposition Leader Bill Shorten has been urged to "toughen the f--- up" by a retired Labor MP.

Steve Gibbons, who served as the member for Bendigo until the 2013 election, has accused Mr Shorten of "constantly letting [Prime Minister Tony] Abbott off the hook" in a straight-talking tweet.

Mr Gibbons, who once referred to former Labor prime minister Kevin Rudd as a "psychopath with a giant ego", was responding to a tweet by Mr Shorten on Tuesday evening.

The Labor leader had linked to a Fairfax Media story about how Mr Abbott's Anzac Day travelling party had requested that the partner of Australia's ambassador to France, Stephen Brady, wait in a car rather than meet the Prime Minister on the tarmac when he arrived in Paris from Turkey.

Ambassador Brady and his partner Peter Stephens were the world's first openly gay ambassadorial couple to be formally recognised when Mr Brady took up the post of ambassador to Denmark in 1999.

Mr Shorten had tweeted of the story: "I sincerely hope this isn't true".

Within minutes, Mr Gibbons had responded directly to Mr Shorten, writing: "Mate, you have to toughen the f---up, you are constantly letting Abbott off the hook, Beazely [sic] did the same #hopeless"

When contacted by Fairfax Media, Mr Gibbons said: "I've got no intention of making any further comment. I'm retired, I'm no longer an MP, I'm no longer on the public purse, so go away."

In 2012, Mr Gibbons took to Twitter to urge Mr Rudd against any move against then prime minister Julia Gillard.

"Only a psychopath with a giant ego would line up again after being comprehensively rejected by the overwhelming majority of his colleagues," he wrote.

Mr Shorten famously withdrew his support for Ms Gillard and switched to Mr Rudd in a move that was pivotal to her demise.

After Labor's election defeat of 2013, Mr Gibbons called on Mr Rudd to vacate his seat in the House of Representatives, saying he would be a 'decaying force in caucus".

He also called on Rudd allies Kim Carr, Doug Cameron and Alan Griffin to quit.

Mr Shorten declined to comment.

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