The UN agency for workers' rights has rejected claims from Tory ministers the body backs the Government's new anti-strike laws.
The Director General of the International Labour Organisation said he was "very worried" workers may be forced to accept a "situation that's below par".
Speaking at the World Economic Forum in Davos, Gilbert Houngbo told the BBC he "has been in discussions" with UK trade unions over the issue.
It comes after both Rishi Sunak and his Business Secretary Grant Shapps claimed the agency supported its plans to impose minimum service levels.
If approved by Parliament the law will force some ambulance staff, firefighters and railway employees to work during industrial action.
The US Labour Secretary Marty Walsh also distanced himself from the proposals at the summit in Davos, according to the BBC.
The ex-union official said that while he did not know about the legislation, "I would not support anything that would take away from workers".
Last week the Prime Minister said the legislation "shouldn't be controversial".
"The International Labour Organisation supports minimum service levels," he added, arguing they are used in a number of European countries.
Business Secretary Grant Shapps also described the ILO as the "guardian of workers' rights around the world" in the House of Commons.
He claimed the agency "says that minimum service levels are a proportionate way of balancing the right to strike with the need to protect the wider public".
Labour's Deputy Leader Angela Rayner said: "Grant Shapps has been ludicrously claiming that his sacking nurses bill has the international seal of approval, but the ILO and the US Labour Secretary clearly beg to differ".
She also accused the Business Secretary of "desperate attempts to justify this shoddy, unworkable and vindictive piece of legislation".
General Secretary of the Trades Union Congress Paul Nowak added: "Ministers have rightly been called out for spinning mistruths. It's time the Government came clean about the draconian nature of this Bill.
"This new legislation is a fundamental attack on the right to strike - and is almost certainly in breach of international law.
"It's little surprise that the ILO and the Biden administration have warned against these spiteful plans.
"These new anti-strike curbs will poison industrial relations and do nothing to resolve current disputes."
