EU mulling legal cases against Poland, Hungary and the Czech Republic over their refusal to take in Muslim asylum-seekers.

The European Union's executive will decide on Tuesday whether to launch legal cases against Poland, Hungary and the Czech Republic over their failure to take in Muslim asylum-seekers to relieve states on the front lines of the bloc's migration crisis, Reuters reports.

The European Commission would agree at a regular meeting to send so-called letters of formal notice to the three countries, the first step in the so-called “infringement procedures” the Commission can open against EU states for failing to meet their legal obligations.

Poland and Hungary have refused to take in a single asylum-seeker under a plan agreed upon in 2015 to relocate 160,000 asylum-seekers from Italy and Greece, which had been overwhelmed by mass influx of people from the Middle East and Africa.

Poland and Hungary have vowed not to budge. Poland's Interior Minister Mariusz Blaszczak was quoted by Reuters as saying on Monday, "We believe that the relocation methods attract more waves of immigration to Europe, they are ineffective."

Meanwhile, Prime Minister Viktor Orban told parliament on Monday, "We will not give in to blackmail from Brussels and we reject the mandatory relocation quota."

The Czech Republic, meanwhile, had initially taken in 12 people from their assigned quota of 2,691, but said earlier in June it would take no more in, citing security concerns.

A spokeswoman in Brussels did not confirm or deny to Reuters the executive would go ahead with the legal cases, but referred to an interview that Commission head Jean-Claude Juncker gave to the German weekly Der Spiegel last week.

"Those that do not take part have to assume that they will be faced with infringement procedures," he was quoted as saying in that interview.