Amid the refugee crisis, the president of the German Federal Office for Migration and Refugees (BAMF) Manfred Schmidt asked to resign "due to personal reasons," a statement by German Interior Ministry said Thursday.

The dramatic increase in numbers of asylum seekers in Germany presents the office with enormous challenges, the statement added.

According to German media reports, Schmidt's authority has come under ever stronger criticism lately because it had not been able to expand the capacity of the agency quickly.

SLOW PROCESSING

On Aug. 31, German Chancellor Angela Merkel said that Germany would intensify its efforts to speed up processing procedures of refugee applications and increase the number of places in preliminary reception centers for refugees.

The German government promised to double the number of employees in total, with 2,000 new jobs to be created in BAMF.

However, the number of asylum seekers has quadrupled. Currently, more than 250,000 applications for asylum have piled up.

German Vice-Chancellor Sigmar Gabriel said on Monday that up to a million refugees may arrive in Germany in 2015, a figure bigger than the current official estimates of 800,000 asylum applications.

Large numbers of refugees have reached Germany in recent days, with more than 19,000 arriving in Munich - the main point of entry - over the weekend alone.

BORDER CONTROLS

Faced with a swell in migrant numbers, Germany took the drastic measure of reinstating border controls on Sunday to slow the influx.

In order to "limit the refugees influx," Germany had decided to reinstate temporarily border control at internal borders, German Interior Minister Thomas de Maiziere announced on Sunday.

Under current European law, Germany is not responsible for most of the asylum seekers, he said, adding the rules of the Dublin Convention are still valid.

German media reported the number of refugees arriving at Munich Central Station declined sharply after the reintroduction of border checks with Austria.

"We were in a situation that registration was no longer possible given the large numbers of refugees. And I believe, also for safety reasons, it is understandable that we must again return to an orderly regime and mechanism," Merkel told reporters on Tuesday, defending the border checks.

Gabriel said the temporary controls were not a permanent closure of borders or suspension of the basic right of asylum, but necessary to maintain control and maintain order.

The vice-chancellor added it was a clear signal to European partners that Germany could not receive all the refugees alone.