(BRUSSELS) - The European Commission, the executive of the 28-nation EU, on Friday defended itself against charges it is failing to act quickly enough to tackle the continent's migrant crisis.

Germany's interior minister Thomas de Maiziere said Thursday that is was "unacceptable that European institutions continue to work at their current slow pace" in finding a joint solution to the crisis.

But in a statement to AFP, Migration and Home Affairs Commissioner Dimitris Avramopoulos hit back at de Maiziere's accusation.

"The commission has worked day and night throughout the summer to offer financial support to member states to set up hot spots and speed up return procedures," Avramopoulos said.

Hot spots are centres to determine whether new arrivals are refugees fleeing war or economic migrants simply looking for work and who must be returned to their home countries.

De Maiziere said he hoped the hot spots would be operational by the end of the year in Greece and Italy, the countries bearing the brunt of the crisis.

The European Commission was also taken aback when French Interior Minister Bernard Cazeneuve announced Thursday that Europe's interior and foreign ministers would meet in Paris in mid-October to discuss how to respond to the huge influx of migrants and refugees arriving at EU borders.

The decision taken by the French and German governments without broader consultation raised eyebrows in Brussels which recalled the need to follow the normal EU channels with proposals submitted to member states and the European Parliament.

Avramopoulos and European Commission Vice President Frans Timmermans are to meet Cazeneuve on August 31 in the northwestern French port of Calais, where throngs of migrants are trying to reach Britain through the Channel tunnel.

"I'm seizing the occasion to repeat that Schengen (Europe's passport-free zone) is non-negotiable and free movement is a fundamental right of the European Union," Avramopoulos said in his statement.

"We should never forget that we are speaking about human beings, people whose dignity must be respected, people for whom we have a moral and legal obligation to protect," he added.