The coronavirus pandemic endangers the basic care of the world's poorest children in developing countries and crisis areas, according to United Nations Children's Fund (UNICEF).

"The pandemic is an existential threat to millions of children," the managing director of UNICEF Germany, Christian Schneider, told dpa.

"Only through internationally coordinated action can we prevent the worldwide health crisis from becoming a global catastrophe for children."

Of particular concern is the virus spreading in overcrowded refugee camps in Greece and Syria.

"Many children there are already suffering from malnutrition and other pre-existing conditions and have little immune support to counter new dangers," Schneider said.

The same applies to children in countries in the Sahel zone and southern Africa. Almost 40% of Africans do not have the opportunity to wash their hands with soap and water at home, which is a key way to stop virus spread.

In Asia, the increasing number of infections in Bangladesh was particularly worrying.

"More than 850,000 members of the Rohingya live there in overcrowded refugee camps," Schneider said. Two years ago, hundreds of thousands of Rohingya fled military violence from neighboring Myanmar to Bangladesh within a short time.

UNICEF is appealing to governments, companies and private donors to now do whatever is possible to ensure the protection and care of vulnerable children.

"We are currently experiencing for ourselves how hard COVID-19 is hitting our country, which has one of the best health care systems in the world," Schneider said.

"In addition to devastating health consequences, the poorest countries are threatened by a social and economic conflagration that will exacerbate the plight of the children."