BRUSSELS, Belgium — The European Union's top justice official warned Monday he will push for retaliatory measures against Canada if it does not take steps toward lifting travel restrictions on Czech citizens by the end of the year.

The EU's Justice and Home Affairs Commissioner Jacques Barrot said Canada's re-imposing of visas on Czech citizens in July "is not acceptable, not just for the Czech Republic but for the European Union as a whole."

He urged Canadian authorities to make progress on lifting the restrictions soon, starting by opening a visa applications centre in Prague as a first step to lifting them altogether.

"If nothing happens by the end of the year, if the Canadians do nothing ... then we will be required to ask the member states whether it will be agreeable to have some form of retaliatory measure," Barrot told reporters.

Barrot suggested the EU could impose visas for diplomatic passport holders as a first sanction.

An EU delegation has already visited Ottawa earlier this month to find a way out of the dispute.

EU interior ministers discussed the Czech visa spat with Canada at talks Monday amid a strong push by the Czechs that all EU nations who are part of Europe's 25-nation borderless travel zone impose retaliatory measures unless Canada relents.

"Visa reciprocity should be the aim of the European Union, but it's also important to see to it that we don't get into some sort of visa war where the situation escalates ... that would be very unfortunate," said Sweden's Immigration Minister Tobias Billstrom, whose country holds the EU presidency.

Canada abolished visas for Czech citizens in 2007, but re-imposed them in July because of concerns over an excessive number of asylum-seekers, most of them from the Roma minority claiming discrimination at home.

Czech and EU officials have called the Canadian move one-sided and wrong and have demanded Czech visa-free status is restored as soon as possible.

Canadian immigration authorities said 3,000 Czech nationals made refugee claims since visas were lifted in October 2007. Less than five refugee claims were filed in 2006, many of them Roma claiming discrimination at home.

Czech officials complain the Canadian refugee system is too generous and open to abuse by fraudulent applications and people seeking profit through organizing such claims.