The European Commission’s defence of a controversial labour market reform shows that the EU executive has not learnt its lesson on Brexit, Poland’s prime minister Beata Szydlo warned on Thursday (21 July).

"We see the need to strengthen national control over EU decision making processes," she added.

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Szydlo spoke to journalists on behalf of the Visegrad countries, whose leaders had gathered in Warsaw for a summit.

Poland took over the presidency of the group - which also includes Czechia, Hungary and Slovakia - on 1 July.

"National parliaments should be the ones that ultimately approve the changes, which the EU wants to make,” Szydlo said, referring to plans to revise the posted workers directive.

Last May, the parliaments of 10 central and eastern EU countries had tried to block the EU initiative to give seconded workers the same pay as their local colleagues.

They teamed up with Denmark - which opposed the procedure for other reasons - and triggered a procedure known as the yellow card, forcing the commission to double-check that the plans did not encroach on national competencies, such as wage setting. Together they represented more than a third of national parliaments in the EU.

EU employment commissioner Marianne Thyssen on Wednesday overturned the appeal , saying that a legal analysis had shown that posting of workers was a cross-border issue that was best regulated at EU level.

Poland, however, remains convinced that the review of the posted workers directive is political.

”Where did this project come from?”, a Polish diplomat in Brussels told EUobserver. ”Where is the proof that posted workers ruin the labour market?”.

”This isn’t grounded in facts but in a will to please certain member states,” he said.

Posted workers account for just 0.7 percent of the labour force in Europe but cause great political controversy.

The richer countries, which tend to host them, say that they contribute to social dumpling - competition through the lowering of labour standards.

Western member states have urged the EU executive to sharpen the rules.

France’s prime minister Manuel Valls at one point threatened to unilaterally cancel existing laws for posted workers - a statement that triggered fury in central and eastern countries.

But the UK - despite Szydlo's remarks - also backed the EU proposal and sent the commission a letter of support.

Poland accounts for almost a fourth of all EU posted workers. The government fears that the proposal will add to bureaucracy and dissuade employers from sending out their staff.

Employment commissioner Marianne Thyssen expressed gratitude to national parliaments for their active involvement and said the commission will continue the political dialogue throughout the legislative process.

An EU source, speaking to EUobserver on the condition of anonymity, wondered whether communications efforts so far had been sufficient.

"We showed the commission stands by its promises, was it wise to do it this way? Shouldn’t commissioner Thyssen should have talked more to the member states beforehand to ensure smooth landing? Do we need this clash all the time? How do we explain this to citizens," the source told EUobserver.

Joint Visegrad position

The four Visegrad leaders said in Warsaw they will work together to give the commission a lesser say in the future.

"We want the Council to set the tone of discussion,” said Czechia’s Bohuslav Sobotka.

The quartet vowed to make a joint contribution to the informal summit on 16 September in Bratislava, where 27 EU leaders - without the UK - will discuss a long-term vision for the EU after Brexit.