The European Commission may end up in court unless it threatens to impose visa restrictions on US citizens.

MEPs in the civil liberties committee demanded on Wednesday (12 October) that the commission makes the threat because citizens of five EU states - Bulgaria, Croatia, Cyprus, Poland and Romania - still need a visa to enter the US.

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"The European Parliament would have a case to take you to court," Dutch liberal Sophie In't Veld told EU migration commissioner Dimitris Avramopoulos.

Swedish liberal Cecilia Wikstroem made similar comments.

"This is a flagrant failure to act and it has to have consequences. This institution [EU parliament] has to act against the European Commission in full compliance with the treaties," she said.

The EU has reciprocity rules on lifting visas with other countries - if they insist that EU nations need visas, then the EU must impose the same obligations on their citizens.

The commission may trigger a so-called delegated act that would threaten to reimpose visas on all visiting US nationals.

But Avramopoulos told the MEPs the EU commission prefers maintaining diplomatic relations amid threats the US would simply impose visas on everyone.

"Yes, we have a legal responsibility. We have a political responsibility as well, the responsibility to ensure visa waivers for all EU citizens and not to lift visa waivers for all EU citizens. It is very clear."

He also noted that there was no chance US Congress would consider removing restrictions just weeks before a presidential election.

The five EU states are denied a visa waiver under a law that says visa requirements can be lifted only when less than 3 percent of applications are rejected. None of the five meet the threshold.

In 2015, the visa refusal rates were 17.3 percent for Bulgaria, Croatia (5.3), Cyprus (3.5) Poland (6.4), and Romania (11.3).

"To give these member states a visa waiver, the United States Congress should change the law and increase considerably this 3 percent threshold," said Avramopoulos.

"There is clearly no appetite in Congress now to do that and you know it."

But MEPs were not impressed.

Spanish centre-right Agustin Diaz de Mera told Avramopoulos to trigger the delegated act anyway.

"You have to initiate that delegated act, it is the tool, the instrument you have in order to negotiate," he said.