German Chancellor Angela Merkel says Afghans coming to Germany in pursuit of better economic circumstances will be sent back to Afghanistan.

Speaking to reporters at a joint news conference with visiting Afghan President Ashraf Ghani in Berlin, Merkel said Germany would meet its humanitarian obligations for Afghans who are in "acute" danger because they worked for foreign forces, such as the German military.

Merkel said that there is not sufficient reason to grant asylum or residency status to refugees who are seeking a better life in Germany, adding that in such cases people would be deported.

"But where refugees come hoping for a better life - and I know that this hope is big for many - that is no reason to get asylum status or residency status here," she said. "And that one needs to think about the 35 million Afghans at home and the land has to develop with this. That is why we will, in such cases, have to send people back to Afghanistan."

Germany is trying to reduce the number of asylum-seekers from Afghanistan. Merkel and Afghan President Ashraf Ghani discussed ways in which Germany could help Afghanistan and stem the flow of Afghan migrants to Germany.

Ghani said that many Afghans have misperceptions about fleeing to Germany and often they "can lose everything along the way."

Merkel said that Germany wants to support the creation of "safe areas" for Afghans in their own country, but there is also a need to empower the Afghan security forces "with regard to refugee movements and illegal migration."

About 800,000 people have arrived in Europe this year, fleeing war and poverty in the Middle East, Africa and Asia, causing the most severe migrant crisis in the continent since World War Two.