TORY plans to impose restrictive thresholds on strike ballots would violate international law, a leading labour lawyer said yesterday. 

Daniel Blackburn, director of the International Centre for Trade Union Rights, believes the Tory manifesto pledge would break standards on workers’ rights set by the United Nations.

The legal expert said it would put Britain’s strike laws on a par with those of Nigeria and Belarus, among the world’s worst countries for workers.

And he told the Star: “The Tory proposals will violate international law and are incompatible with our international obligations.”

The damning verdict delivered a blow to PM David Cameron’s claim that the Tories are now the “real party of working people.”

Britain already has some of the most restrictive trade union laws in Europe, but the Tory manifesto launched by Mr Cameron in Swindon promises a 50 per cent turnout threshold on strike ballots if they win the general election.

And workers in health, education, fire and transport face even more restrictions. 

The manifesto states: “Industrial action in these essential services would require the support of at least 40 per cent of all those entitled to take part in strike ballots — as well as a majority of those who actually turn out to vote.”

TUC general secretary Frances O’Grady said the move would make it “almost impossible” to call a legal strike. “No other mainstream political party in the democratic world has suggested such a fundamental attack on this basic human right,” she said. 

If implemented, Britain would become one of a tiny group of countries to impose a double threshold on strike ballots, including heavily criticised human rights violators such as Nigeria and Belarus. 

Mr Blackburn said the policy breaks the International Labour Organisation’s (ILO) convention 87, protecting freedom of association and the right to organise. 

He explained: “The ILO has confirmed that, in strike ballots, only votes that are actually cast can be counted, and that the assessment of quorum and majority must be fixed at a reasonable level. “Setting a quorum which requires a high turnout of all those entitled to vote is obviously not reasonable, given participation levels in voting generally.”

Unions also pointed out the hypocrisy of Mr Cameron imposing a threshold that only 15 Tory MPs matched at the 2010 general election.

Health Secretary Jeremy Hunt and Mr Cameron himself both managed just 43 per cent, while Chancellor George Osborne achieved 37 per cent.

RMT leader Mick Cash said it showed there was “one law for the political class and another for the working class” and vowed the plans would meet “the fiercest possible resistance.”

Unite leader Len McCluskey added: “If David Cameron wants to increase participation in ballots then he should join us in demanding the right to secure online voting and the ability for workers to vote in their workplaces.”