A German official condemned the spate of arson attacks on migrant refugee shelters as the European nation grapples with an unprecedented influx of asylum seekers. Most of the refugees who have reached Germany so far this year are from Kosovo, Syria, Serbia, Albania, Iraq and Afghanistan.

"I feel shame for the hatred of foreigners out there on the streets of Germany," Justice Minister Heiko Maas told local newspaper Bild on Tuesday, cited by Reuters, after the country's interior ministry reported 150 attacks on refugee shelters in the first half of this year -- nearly double the figure recorded last year in the same period.

The German government says it expects to receive 450,000 asylum seekers this year amid a massive refugee crisis as people flee violence in the Middle East by crossing into Europe through the Mediterranean Sea, often in rickety or unsafe boats. The European Union launched a joint naval effort to address the issue, but the region is still bracing for a heavy inflow of refugees.

Maas said that despite the "irrational fears and violence," he was impressed by a surge of goodwill toward asylum seekers. 

However, experts warn that a pattern of attacks against immigrants is yet to die down. "These acts show us that right-wing extremist groups are on the rise," Andreas Zick, director of the Institute for Interdisciplinary Research on Conflict and Violence at Bielefeld University, Germany, told Deutsche Welle. "The arsonists want to make clear that after all the protests against refugee homes, they are actually doing something and taking matters into their own hands."

Other leading German public figures have also spoken out against the attacks. Cardinal Reinhard Marx, president of Germany's bishops' conference, said the Catholic church condemned acts of "hatred and violence."

"Some groups are trying to poison the climate in our society and to sow hatred," Marx reportedly said on Friday. "We must never tolerate this."

German President Joachim Gauck also denounced the rise in such attacks earlier in July. "We are seeing xenophobic attitudes taking root and that some people aren't even shying away from carrying out attacks," he said in a speech in Berlin. "I'm referring to what we have recently experienced again with these vile attacks on refugee homes. It's unbearable."

A populist movement known as the Patriotic Europeans Against the Islamization of the West, or Pegida, has also channeled anti-Islamic sentiment in the country. The group's January protest at Germany's Brandenburg Gate was dwarfed by a major counter-rally. Lights were also turned off across Berlin in a mark of disapproval against the anti-immigrant protest.