Anthony Joshua is undergoing rigorous anti-doping testing to KO Joseph Parker’s baseless “king of steroids” slur.

The Kiwi WBO champion casually threw out the controversial jab in a bid to speed up the big-fight negotiations and he retracted it and apologised swiftly after.

AJ revealed at the first press conference that he spends around £30,000 per fight getting tests by the UK anti-doping authority, as well as WADA.

And the IBF and WBA champ even revealed he would invite the testers – who must know his exact whereabouts twice a day – into a nightclub with him to maintain his squeaky clean reputation.

One of AJ’s team revealed on Thursday on his Instagram account that the Watford hero had been tested three times inside five days and twice consecutively.

After announcing the fight, AJ and promoter Eddie Hearn hit back at the unfounded steroid claim by revealing the lengths they go to meet regulations.

AJ said: “I sign up three months in advance every time and I have to give them two slots in the day where I definitely will be – so they are able to drug test me.

“I am not trying to prove anything. I pay my money.”

And Hearn – who has serious concerns the massive fight with Tyson Fury could turn to dust – added more detail on the costly process.

The Matchroom kingpin said: “We pay something like £30k every fight, to make sure the fighters are tested.

“As soon as the contract is signed, that testing is under way, that’s WADA. We optionally sign up for that

“We are also with UKAD, through the BBBofC and that’s 365 days a year, random whereabouts testing.

“The last three or four fights we have been test eight times in camp by UKAD and WADA over a 12-week period.

“We are also on 365 days a year WADA testing for the WBA. People ask ‘why is he not on the WBC (testing programme) but he is not a WBC fighter.

“The WBA now have 365 days testing and he pays for additional for random testing and the UKAD.

“He is the one pushing for a clean sport.”

The Sun