LABOUR MPs will not back trade unions which stage illegal strikes, Tom Watson, the party’s deputy leader, has insisted after Jeremy Corbyn and John McDonnell repeatedly dodged the issue.

Mr Watson said that while Labour was committed to changing existing trade union legislation, it did not want people to break the law.

The Midlands MP said the Unite trade union boss Len McCluskey - who has said he is ready to defy a legal requirement that strikes must be backed by a ballot with a turnout of more than 50 per cent - now accepted Labour MPs could not support illegal industrial action.

"I have actually received a letter from Len McCluskey this week where he says he accepts Labour MPs aren't going to support calls for illegal strike action,” explained Mr Watson.

"We don't support people breaking the law. We don't want people to break the law, we are democrats.

"We are going to change the law so that trade unionists can have greater rights because we think our current framework of laws is very unfair," said the Labour deputy leader.

Earlier, appearing on BBC One's Andrew Marr Show, Mr Corbyn attempted to sidestep questions about whether or not he backed unions calling illegal strikes.

“This law is something that is really unfair,” insisted the party leader. “No MP, very few MPs, get more than 50 per cent of their electorate; I was one of the very few who does.”

Asked if he would support workers going on strike regardless of the law, Mr Corbyn refused to rule it out. “The clear answer is this: I support the campaign for a decent pay level in the public sector.

“I will ensure that a Labour government repeal the existing trade union law and bring us in line with the international labour organisational conditions.”

Repeatedly pressed on whether or not he would support unions defying the law, the Labour leader replied: "I will be with those workers demanding a decent pay rise."

Mr McCluskey called for the Prime Minister to review the law, saying he would support the 50 per cent threshold if there were workplace ballots rather than "archaic" postal votes.

He told ITV's Peston On Sunday: "I'm urging the Prime Minister not to push workers outside of the law."

He confirmed Mr Watson's comments that he did not expect Labour to back illegal strikes.

"I don't expect the leadership of the Labour Party - or any Labour MP - to support a call to be outside of the law. I know that they are opposed to the current law and they will do all that they can inside Parliament to change this law.

"I'm not looking for that support, I'm not looking to be pushed outside of the law."

Mr McDonnell also repeatedly refused to say whether or not he would back illegal strikes, saying the issue did not arise as strike ballots would meet the turnout threshold.

"I don't think anyone understands properly the strength of the anger out there.

"You watch what will happen this coming winter. These strikes have been provoked by this Government as a result of pay being below inflation,” he added.

Meanwhile, Mr Corbyn, 68, indicated he would want to serve for 10 years as Prime Minister if Labour won power. This would keep him in Downing Street until the age of 83 if Labour won the next scheduled election in 2022.

The Labour leader told The Sunday Mirror: “I’m very fit and I’ve grown into the job. I enjoy every day and I know my own mind.

"I’ve waited all my life to see our country transformed, to bring about social justice, and I’m relishing the prospect of government.”

He later told the Marr Show: "What I said was that we need at least two terms of a Labour government to start to address issues of poverty and injustice and inequality in Britain and to build the houses we need in this country.”