Malcolm Turnbull insists he’s not a hater but Bill Shorten is a fake. Picture: Gary Ramage

But the Prime Minister insists he’s “not a hater”.

Mr Turnbull said this morning the explosive smackdown had been a long time coming but insisted there was no speech writer.

After months of being attacked for his wealth and called “Mr Harbour-side mansion”, the PM decided to hit back.

“It was absolutely extempore, off the cuff ... I didn’t know he was going to move a censure about me,” Mr Turnbull told Melbourne’s 3AW radio.

“I’ve copped it sweet for a while now and I gave him something in return and he didn’t like it,” he said.

MORE: Australia’s best political smackdowns

Labor claims the attack on Bill Shorten was to deflect attention from the Coalitions internal woes. Picture: Kym SmithSource:News Corp Australia

In the savage Question Time rant on Wednesday, the Prime Minister called Shorten a “parasite” and a “sycophant”

“There was never a union leader in Melbourne that tucked his knees under more billionaires’ tables than the Leader of the Opposition — he lapped it up,” Mr Turnbull told the chamber.

When asked if it was a personal dislike this morning, Mr Turnbull said he wasn’t “a hater”.

But he also said the best speeches were from the heart.

“It is important to show him up for the hypocrite he is,” Mr Turnbull said.

“The fact is if you want to stand up like Shorten and play the politics of envy and go on and pretend you’re some horny-handed son of toil whose worked his way up from the bottom and always battled for the common man and stood up to the rich and powerful, then you better be fair dinkum — and he isn’t, he’s a fake.”

Deputy Prime Minister Barnaby Joyce loved the Prime Minister’s speech. Picture: AAP Image/Lukas CochSource:AAP

Mr Turnbull had prepared at least a few lines before his speech; he cited a 2011 and 2012 quote of Mr Shorten’s arguing for corporate tax cuts.

Shorten had been Assistant Treasurer at the time and had said cutting the company tax rate would increase productivity and investment.

On Wednesday, the Opposition leader had attacked the Government’s social welfare reforms, accusing Mr Turnbull of supporting the top end of town while making things harder for families, young people and pensioners.

Malcolm Turnbull has confirmed his blistering Question Time attack on Bill Shorten was off the cuff. Picture: Kym SmithSource:News Corp Australia

Defence Minister and Leader of the House Christopher Pyne has claimed some responsibility for the smackdown but denied he wrote the speech.

Mr Pyne spoke to Mr Turnbull briefly before he launched the attack on Shorten.

“I provided Malcolm with some of the material that I keep in my own hands (but) all those best lines were his lines,” he told Nine Network.

“The only role I had was deciding whether we should go ahead with it (a Labor motion put to the lower house) and speak to it rather than use our numbers to shut it down.”

Labor has accused the Prime Minister of trying to shift the attention off his own party’s woes as the vitriolic attack came a day after Senator Cory Bernardi left the Liberal Party and Sussan Ley’s resignation over travel expenses this summer.