THE boss of Britain’s biggest union has said he would support illegal strikes if the one per cent public- sector pay cap is not lifted by Westminster.

Unite leader Len McCluskey said public sector industrial action was “very much on the cards”.

The UK Government has lifted the cap for prison and police officers in England and Wales – but, as yet, not for other public-sector workers.

Under a new law introduced in March, ballots for strike action now must have at least a 50 per cent turnout for industrial action to be legal.

McCluskey gave the illegal strike warning as GMB trade union members at the Sellafield nuclear plant gave notice of a strike on September 27 in a pay dispute.

McCluskey told the Trade Union Congress conference in Brighton: “If they [Unite members] haven’t managed to hit an artificial threshold this Government has foolishly put on to the statute books, then I will stand by our members and we’ll all live, including the Government, we’ll all live with the consequences of that.” The conference voted to support coordinated campaigns.

“In terms of the concept of co-ordinated public service workers’ action, then yes I think that is very likely and very much on the cards,” said McCluskey.

“We will always stand shoulder-to-shoulder with our members. If the Government has pushed us outside the law they will have to stand the consequences.”

The unions are campaigning for a five per cent increase for millions of public-sector workers.

Pay was frozen in 2010 for all but the lowest earners, with increases set at no more than one per cent a year from 2013.

Labour’s shadow justice secretary and shadow lord chancellor Richard Burgon has refused to say if he would support a strike called without a 50 per cent ballot turnout, saying such a scenario was “hypothetical”.