Opposition Leader Bill Shorten still hasn’t publicly acknowledged he told a lie, despite admitting it to Melbourne broadcaster Neil Mitchell off-air.

Tuesday’s episode of The Killing Season revealed Kevin Rudd secretly met Mr Shorten in 2013 to secure his support before Mr Rudd mounted a successful leadership challenge against Julia Gillard, who had seized the leadership from him three years earlier.

On Mr Mitchell’s program, Mr Shorten was called on to explain the revelation, as he had made comments to the contrary in 2013.

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“I think he has got questions to answer,” Mr Mitchell said.

“He has been caught out deliberately misleading you and me about his involvement in the 2013 leadership battle.”

On June 21, 2013 Mr Shorten said he had not “spoken to Kevin Rudd”, and would “continue to support” Ms Gillard. The meeting with Mr Rudd had been held two days prior, according to the show.

According to the broadcaster, Mr Shorten called him during the 11am news on Tuesday and apologised for his conduct.

Late on Tuesday night, Mr Shorten was interviewed at Parliament House in Canberra.

A journalist asked him “Have you lied, Mr Shorten?”

“I do regret my remarks, unequivocally, I regret them, and I’ve conveyed that,” Mr Shorten responded.

“I was very conscious of not causing further problems for Labor.”

He said it was a “tough time” for Labor in 2013 and he was trying not to “make life harder” for the party.

“I do regret my remarks, the fact of the matter is I had met with Kevin Rudd, I didn’t pledge my support. It was very tough times and I did not want to, at that critical juncture, make life harder for Labor than it already was,” he said.