The pro-Russian YouTuber dubbed the 'Aussie Cossack' is being sought by police after the Ukrainian ambassador claimed he leaked his phone number. 

Simeon Boikov prank-called Vasyl Myroshnychenko live on his YouTube show on Thursday, broadcasting the diplomat's number to his 150,000 followers. 

Mr Myroshnychenko, who is Ukraine's ambassador to Australia, said he was inundated with dozens of threatening calls and messages following the stunt. 

A spokesperson for NSW Police told Daily Mail Australia they are seeking Boikov's arrest after the NSW Parole board revoked his parole licence. 

The YouTube video was titled 'Ukrainian Ambassador prank over Tennis Australia ban for Russians' and has been watched by 13,000 viewers.

Boikov, a vocal supporter of Russia's invasion of Ukraine, is said to have created the video following the ambassador's call for Tennis Australia to reconsider banning Russian and Belarusian players from the Australian Open. 

'Now he's all huff and puff and he's all angry about the Australian open,' Boikov said in the video. 

'But what he did on the statement that he released, he released his mobile number. There it is there on the screen...

'So the Ukrainian ambassador's mobile number makes its way into the Aussie Cossack's sphere of influence, you could say.

'Let me know in the comments section what we should do next. Should we give him a call?' he asked his viewers. 

Mr Myroshnychenko said he had about 30 phone calls, text messages and voicemails from people since the video.

'(Mr Boikov has) released my phone number to his network who started calling me, harassing me, intimidating me with insults and threats,' Mr Myroshnychenko told The Australian.

He said some callers were 'more sophisticated' while others just swore at him. 

The Australian Federal Police said they were aware of the matter, and were working with the diplomatic mission.

Asked if he was concerned for his safety, Mr Myroshnychenko replied: 'Of course'.

'Of course it's uncomfortable, it's a distraction.' 

Boikov insisted he had not encouraged anyone to harass the diplomat.

'I don't know any of the people that rang him,' he said. 'I didn't ask anyone to ring him. Maybe it's paranoia'.

The YouTuber is believed to be in the Russian consulate in Sydney and is reported to have applied for Russian citizenship.

He is also said to have asked for political asylum after he was charged with assaulting an elderly man at a Ukrainian rally in December.

Boikov was charged with assault occasioning actual bodily harm and granted conditional bail and said he was confident he would beat the charge by claiming 'self defence'.

He told The Guardian the ambassador's phone number was already available online and he didn't tell anyone to harass the ambassador.

'He only has himself to blame if people are ringing him and getting backlash from the Australian public,' said.

Daily Mail Australia has approached Simeon Boikov and Vasyl Myroshnychenko for comment.