A spate of attacks in southern Germany since July 18 have stoked concerns about unprecedented immigration in the country since last year.

Two of the five attackers recently entered Germany from Syria, another was from either Pakistan or Afghanistan.

Chancellor Angela Merkel, however, is adamant that Germany can cope with the challenge of integrating refugees and the threat of Islamist violence.

Angela Merkel is in the spotlight once again... for her decision to welcome refugees. She rebuffed calls to reverse her policy..

"The fundamental principle which says that a country like Germany can not abandon its humanitarian responsibility, but rather must accept it, is valid," she said.

"Events have created a strong feeling of insecurity, people are scared, that is obvious... but despite this I remain convinced that fear can not be a foundation for political action."

Last year, more than 1 million asylum-seekers were registered in Germany.

"Today I am convinced, just I have been in the past, that 'we can do it' -- it is our historical duty and this is a historic challenge in times of globalisation. We will get there and we have already achieved a lot in the last 11 months," Merkel said.

Multiple attacks in the past weeks stunned Germany. They left 13 people dead and dozens wounded.

Three of the five assailants were asylum seekers, and two incidents were claimed by the Islamic State group.

Merkel said she would not allow extremists to keep her government from being guided by reason and compassion.

She also announced a string of new security measures including tougher background checks on asylum-seekers, and speeding up deportation of those who have been rejected.

Bavarian Interior Minister Joachim Herrmann said his state would hire some 2,000 additional police officers by 2020 and set up new offices to fight Muslim extremism and cybercrime.