WASHINGTON (AFP) - Diplomats from the 28-member European Union on Monday (Dec 14) warned they could respond in kind if the United States makes good on plans to end visa-free entry for some EU nationals.

After the Nov 13 terror strikes in Paris and as part of wider anti-terror efforts, the US House of Representatives voted last Tuesday in support of the Visa Waiver Programme (VWP) Improvement Act of 2015, a measure the White House supports.

The Paris strikes were conducted by extremists who could have travelled to the United States without a visa. The Bill, which still requires Senate and White House nods, would bar people who travelled after March 1, 2011 to Iraq and Syria - as well as Iran and Sudan - from participating in the visa-free programme.

"Compulsory biometric checks at the port of origin would represent the de facto introduction of a visa regime in all but name," EU Ambassador to the United States David O'Sullivan said in an editorial in The Hill, on behalf of ambassadors to the US of EU member states.

"Such indiscriminate action against the more than 13 million European citizens who travel to the US each year would be counterproductive, could trigger legally mandated reciprocal measures, and would do nothing to increase security while instead hurting economies on both sides of the Atlantic."

The US acknowledged potential for strains over any changes.

"We have been in touch with and will continue to be in touch with European leaders about their concerns about the programme," State Department spokesman John Kirby said. "It's an important programme, we recognise that."

VWP is available to citizens of 38 countries, largely US allies and relatively stable developed democracies.

Many are in Europe, including Belgium and France, the home countries of several of the Paris attackers.

Created in 1986 to help facilitate travel to the US, the programme allows applicants to fill out a detailed form online and pay a small fee, rather than apply at US consulates.