UNITE is the victim of a “sustained witch-hunt” by the right wing of the Labour Party because of its support for Richard Leonard, the left-wing candidate in the Scottish Labour leadership race, Pat Rafferty, the union’s Scottish Secretary, will claim today.

Speaking at Unite’s policy conference in Aviemore, Mr Rafferty will also accuse Labour MP Ian Murray, the former Shadow Scottish Secretary and a supporter of the centrist candidate Anas Sarwar, of hypocrisy by “preaching unity but practising division”.

He will launch a direct attack on Mr Sarwar, the Glasgow MSP, over his and his wife’s decision to educate their son privately.

The union leader will also suggest the centre of power in Labour is now firmly on the Left and that the “careerist tendency in Labour, which sees its grip of Labour slipping, can squeal as much as they like”.

Last night, Jeremy Corbyn addressed Labour members in Edinburgh and is due to speak at the Unite event later today. Tomorrow, Mr Leonard will also address the conference.

The UK Labour Party leader has made clear he is staying out of the Scottish leadership contest, having stressed he would work with whoever wins on November 18.

In remarks that will do little to lower the temperature in a heated leadership contest, Mr Rafferty will say: “Unite is being subjected to a sustained witch-hunt from the right wing of the Labour Party aided and abetted, unfortunately, by sections of the media.”

He will forcefully dismiss claims that Unite, the country’s largest trade union and Labour’s biggest donor, has tried to fix the leadership contest as “absolutely outrageous and totally unfounded,” and will insist the union has “not broken a single rule”.

The union chief will say: “So my message to Ian Murray…and his like on the right of the party is: don’t try and use Unite in an attempt to cover up your own failing campaign for Anas Sarwar. It’s not Unite who are rigging the vote. It’s not Unite giving false news stories to the media. And it’s not Unite who preach unity and practice division.

“And to Anas Sarwar I would simply ask this: what standard does Scottish public education need to be at before you would send your children there?”

Mr Rafferty will say the party and its supporters now have a “great opportunity to build on this new radical agenda by electing a strong trade unionist - Richard Leonard - as the next leader of the Scottish Labour Party”.

He will point out how in 1900 the Labour Representation Committee was established to give the working people in Britain a political voice in the country’s politics and that it was built on the trades unions.

“The re-engagement of the unions with Labour in Scotland is replenishing and re-invigorating the party. The careerist tendency in Labour which sees its grip of Labour slipping can squeal as much as they like. Unite and its members are walking in the footsteps of history.”

Meanwhile, Dennis Skinner, the Labour left-wing veteran, has announced his support for Mr Leonard’s candidacy. In a video message to party members, he said: “Scotland has always been a left-wing country and that’s why it’s important to put Richard Leonard in charge.

“We need to have an alternative to the Scot Nats, who masquerade as the left-wing party in Scotland.”