Paris (AFP) - The French government on Tuesday condemned two mayors who said they would only take in Christian refugees, as the country prepares to receive the first tranche of some 24,000 migrants.

"You don't sort (refugees) on the basis of religion. The right to asylum is a universal right," Prime Minister Manuel Valls said Tuesday evening, hours before some 200 are expected to arrive from Germany.

Under pressure to respond to Europe's biggest migrant crisis since World War II, President Francois Hollande announced Monday that France would take in 24,000 people over two years.

As a first gesture of solidarity with Germany, which is shouldering the lion's share of the new arrivals, France will rapidly take in 1,000 Syrians, Iraqis and Eritreans, he said.

But the decision caused unease in some quarters, and the mayor of the central town of Roanne, Yves Nicolin, said Monday he would only take in Christians in order to be "certain they are not terrorists in disguise".

Roanna would settle "a dozen families, providing they are Christian refugees who are persecuted in Syria by Daesh (the Islamic State group) for being Christians," he said.

Damien Meslot, mayor of Belfort in eastern France, also said he would only consider taking in Christian families from Iraq and Syria because "they are the most persecuted".

The mayors both belong to the main opposition party of former president Nicolas Sarkozy.

Their comments recall similar remarks from Slovakia, which said in August it would only accept Christian refugees from Syria, arguing Muslims would not feel at home there.

Interior Minister Bernard Cazeneuve condemned the mayors' remarks, adding that France "must be prepared to take in all those who are persecuted regardless of their religion and their background".

"I really don't understand this distinction. I condemn it and I think it's dreadful," Cazeneuve told France 2 television.

"A whole series of minorities are being persecuted in the situation in Syria," he added. "Christians from the Middle East must be welcomed but there are also Muslims and other minorities who are persecuted with the same degree of barbarity."

The controversy comes as 200 refugees are expected to arrive from Germany on Wednesday, the French Red Cross said.

France's interior ministry said the decision as to how the asylum-seekers were distributed around the country would be taken by a separate government office, not by individual town halls.