A food bank in Germany is being criticized for its decision to stop serving more foreigners, who make up a growing percentage of its users.

The food bank in the western city of Essen announced last month it will only register new users if they prove they've got German citizenship, saying young foreign men are scaring away elderly people and women.

"We want the German granny to be able to keep coming to us," said Joerg Sartor, chairman of the charitable group that serves free meals to the poor in the western city of Essen.

He said especially German elderly people and single mothers had been gradually displaced over the past two years as the share of migrants had risen to three-quarters of recipients.

More than 1.2 million asylum seekers have come to Europe's biggest economy since 2015, more than half from war-torn Syria, Iraq and Afghanistan, in mass influx that sparked a xenophobic backlash.

The website of the "Essener Tafel" charity said it had taken the step in order to avoid frictions between needy locals and foreigners that could harm acceptance of the newcomers.

"Since the number of foreign citizens among our clients has risen to 75 percent in recent years ... we are forced to only accept customers with German identity cards in order to facilitate proper integration," it said.

The charity announced the change in December and implemented it in mid-January, but it was only widely reported on Thursday, initially by the newspaper Westdeutsche Allgemeine Zeitung (WAZ).

The group, like hundreds of similar charities nationwide, collects surplus food that would otherwise be discarded by supermarkets and other businesses to prepare and serve it to the poor.

Typically, people have to register to qualify for regular free meals by proving that they are recipients of unemployment or other social benefits.

Sartor told the WAZ daily that his charity would maintain the additional demand that new clients show German identity papers to register "until the balance is restored".

There are more than 930 Tafel organizations in Germany, with around 2,000 distribution points.

According to the national association Tafel Deutschland, about 60 per cent of its users nationwide are of non-German origin.