The Strikes (Minimum Service Levels) Bill would require public services to deliver a minimum level of service during industrial action, with unions being sued if they fail to comply.
Critics of the bill, including the Trades Union Congress (TUC), say this would limit the power of workers to use strikes in negotiation about pay and conditions.
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Strikes and industrial unrest: FAQs
Signatories to the statement include former Italian prime minister Giuseppe Conte, the Australian Labor Party and Spain’s coalition government parties PSOE and Unidas Podemos.
The statement condemned the legislation as interfering with the right to strike.
It said: “The UK already has some of the most draconian restrictions on trade unions anywhere in the democratic world and workers in the UK are faced with disproportionate regulatory hurdles before participation in a strike can be considered legal.
“Despite this, the UK government is set on further rolling back worker protections and freedoms.”
UK ministers have previously compared the legislation to laws in France, Italy and Spain.
However, the new bill would allow the UK government to sue unions and dismiss workers who do not meet minimum service levels, none of which is legal in those countries.
The politicians’ statement condemned the comparison to other international strike legislation and called on the UK government to withdraw the bill.
It said: “We reject the UK government’s attempt to limit workers’ rights and its attempt to justify it with comparisons to international norms.
“The right to strike is guaranteed in international law by a succession of important treaties.
“The ability for people to collectively withdraw their labour is a fundamental right in a democratic society. We support the Trades Union Congress in calling on the UK government to abandon this bill.”
Tim Sharp, TUC senior employment rights officer, said the bill would escalate current workforce dissatisfaction.
Speaking to HR magazine, Sharp said: "The Conservatives have launched a full-frontal assault on the right to strike.
“Employers should oppose the bill in its entirety; it will likely poison industrial relations and exacerbate disputes, rather than help resolve them.”
He said the legislation is being introduced at a particularly challenging time for workers.
There has been widespread industrial action this year by NHS workers, rail workers, teachers and civil servants.
Only 32% of workers believe their pay is fair, according to a study from management consultancy, Gartner.
Sharp added: “With inflation running at over 10%, the last thing working people need is for ministers to make it harder to secure better pay and conditions.
“Ministers must drop this spiteful bill and protect the right to strike.”
Matt Jenkin, employment lawyer at law firm Moorcrofts, said the impact the legislation would have is debatable.
Speaking to HR magazine, he said: “Whilst it may reduce the impact of strike action it won’t remove disruption entirely.
“Whenever unions have been faced with legislation that makes strike action more difficult, they have adapted to it and this could well be no different.”
