The chief of staff of Britain’s largest trade union Unite has launched a group supporting pro-Russian separatists in Ukraine.

Rebel groups are now widely suspected of shooting down Malaysia Airlines Flight MH17 in the east of the country.

Andrew Murray, right-hand man to the Unite general secretary Len McCluskey, spoke at the inaugural meeting of a campaign called Solidarity With The Antifascist Resistance In Ukraine (SARU) in June.

Andrew Murray has launched a group supporting pro-Russian separatists in Ukraine

Introduced as representing the Communist Party of Britain, rather than Unite, Mr Murray, 56, a former member of the TUC General Council, branded the Kiev government ‘fascist’.

Mr Murray – whose union has given £28.9 million to Labour since it was formed in 2007 – also derided Prince Charles for comparing President Vladimir Putin to Hitler, adding that he rejected ‘this focus on Mr Putin, when our enemy is at home’.

He added: ‘We have to take a stand here in Britain, which is the main ally of the United States… which is standing with the Kiev government and backing its horrendous assault on its own people.

‘We must demand that our government stops supporting EU and Nato expansion and stops supporting the Kiev government.’

Since the airliner was shot down last month, with the loss of all 298 people on board, SARU has held a demonstration outside the Ukrainian Embassy in London, against ‘repression in Eastern Ukraine’.

A posting on the SARU website read: ‘Protesters also spoke up against the media coverage of the downed Malaysian flight MH17 over Eastern Ukraine, criticising the haste [sic] attribution of guilt to Russian President Vladimir Putin.’

Elsewhere it suggested that the airliner flew ‘lower than usual over the danger zone at the request of the Ukrainian dispatchers’.

Unite general secretary Len McCluskey, the union's chief of staff has launched a group supporting pro-Russian separatists in Ukraine

Critics say that in return for its funding, Unite exerts an increasingly tight hold over Labour. Some observers describe Murray as the single most powerful man in British unions. Political commentator Dan Hodges wrote in 2012: ‘McCluskey fronts the show, but Murray runs it.’

Justice Secretary Chris Grayling highlighted the close bond between Unite and Labour last week, saying: ‘What Len McCluskey at Unite asks this week, next week will become Labour policy.’

Mr Murray’s rhetoric strikes a very different tone from that of Deputy Labour Leader Harriet Harman, who said after the attack: ‘This is the moment for a strong and determined EU to step up to its responsibilities and confront the Russian actions.’

Mr Murray describes himself as a critic of President Putin in recent speeches over Ukraine, but reserves his most strident criticism for the UK, US, Nato and the EU.

Two years ago, father-of-four Mr Murray, who owns a smart £900,000 townhouse in a gated development in the London Borough of Islington, told a Communist Party of Britain meeting: ‘If the Government continues to govern in this way, it’s up to us to make the country ungovernable’.

Veteran anti-fascist campaigner Gerry Gable, the former editor of Searchlight magazine, described SARU as ‘a scam’ and said he turned down an invitation to its launch at London University’s School of Oriental and African Studies.

Mr Gable told The Mail on Sunday: ‘The Communist Party of Britain have been supporting this initiative to work with the “anti-fascists” in Ukraine, and I’ve been saying to people, “Have you lost your mind?” Putin is an absolute scumbag – you can see the way they’ve treated the media there with people getting themselves shot on their doorstep, disappeared and so on.

‘The so-called Solidarity With The Antifascist Resistance in Ukraine is simply a scam.’

Mr Murray said: ‘I entirely condemn the shooting down of the Malaysian airliner. It’s simply not true to say I contradict the Labour Party position on this crime, since my one speech to the SARU was made long before the airliner was shot down. Since June 2, I have spoken at no further meetings organised by SARU, nor otherwise participated in its activities.

‘I support opposition to the war in Ukraine and to the Far Right in the Kiev government that includes hard-line fascists, but I have no time for Putin or his regime.

‘There was no suggestion I was speaking on behalf of Unite, which has not discussed this issue.’

A disaffected former Unite member – and one-time Labour parliamentary candidate – Jonathan Roberts described Mr Murray’s views as ‘abhorrent’ last night.