A union is to launch a judicial review against the government’s new law to stop strike action in the Border Force.

The Public and Commercial Services union (PCS) said it will use the Human Rights Act to challenge the new law aimed at ensuring minimum levels of service during strikes.

The announcement was made by PCS general secretary Mark Serwotka at a huge rally marking the 40th anniversary of the ban on trade unions at the GCHQ communications headquarters.

The new law allows employers to order staff to come into work during strike action to ensure minimum service levels are met.

It is a fundamental human right of any worker to withdraw their labour to protect their terms and one we shall defend on behalf of our members in the Border Force

The PCS said it will argue this contravenes the right to strike enshrined in Article 11 of the European Convention on Human Rights.

Mark Serwotka said: “Forty years on from Margaret Thatcher banning unions at GCHQ, a Conservative government is once again attacking trade unions.

“So it’s fitting today, as we mark the courage and determination of those workers who refused to hand in their trade union membership, that I can tell you we will be fighting this new injustice in the courts.

“It is a fundamental human right of any worker to withdraw their labour to protect their terms and one we shall defend on behalf of our members in the Border Force.”

The union is being represented by Thompsons Solicitors, for whom partner Neil Todd said: “Minimum service levels are very difficult to justify in a legal regime which is already so restrictive when it comes to trade union rights.

“The Border Security Minimum Service Regulations provide an unlimited freedom to undermine the right to strike, which we contend is unlawful as it exceeds powers under the Strikes Act. The government have been given 14 days to respond to our letter”.

This case is just the beginning. We will use every lever at our disposal to fight these cynical laws

TUC general secretary Paul Nowak said: “The TUC and the whole union movement will stand with PCS every step of the way with this legal challenge.

“These new minimum service level regulations represent an unprecedented attack on our fundamental right to strike.

“This case is just the beginning. We will use every lever at our disposal to fight these cynical laws.

“These past few weeks have shown that these laws are unworkable. Any half-decent employer will steer well clear of minimum service levels.

“Ministers have designed these laws to escalate disputes – not resolve them. They’re undemocratic and likely illegal – and they’ve dragged us further away from European democratic norms.”

Thousands of trade unionists joined the rally in Cheltenham.

Mr Nowak added: “If any employer dares to use minimum service levels, they will face the full force of the union movement.

“Unions won’t stop until these spiteful laws are off the statute book for good.”

Unite general secretary Sharon Graham, speaking about the minimum service levels law, told the rally: “This legalisation puts this Government at war with workers. We will use every tactic in our armoury to push back any employer who uses this anti-union legalisation.

“And make no mistake, any employer who chooses to serve the first work notice – this will be seen as a hostile act; a stake in the ground – and we will escalate and we will win.”

Matt Wrack, Fire Brigades Union general secretary, said: “In its final months in office, this dying Tory Government is seeking to prevent workers from striking even when they have a democratic mandate to so.

“In the fire and rescue service, as in other sectors, this could amount to a de-facto strike ban.

“The trade union movement cannot and will not accept this attack on basic democratic rights.

“The Tories’ agenda is about driving down wages and conditions while the rich get richer.

“The TUC is committed to a campaign of mass resistance to the Minimum Service Levels Act, up to and including non-compliance, and we look forward to a Labour government repealing both it and the 2016 Trade Union Act within its first 100 days.”