German Chancellor Angela Merkel on Thursday defended her open-door policy towards refugees, despite a series of attacks in the country in July.

An asylum seeker from Afghanistan armed with an axe and a knife attacked passengers on a train in Wuerzburg and an asylum applicant from Syria blew himself up outside a music festival in Ansbach. Both of the attackers claimed allegiance to Islamic State group.

In Reutlingen, a Syrian killed a woman and injured two others in what was believed to be a domestic incident. In Munich, a German-Iranian shot dead nine people before killing himself.

Merkel said those assailants who used their time in Germany to plan and launch attacks "shamed the country that welcomed them."

More than a million of asylum-seekers were registered in Germany in 2015.

At a news conference in Berlin the German Chancellor announced adjustments to current refugee policy and a nine-point plan to increase security.

Proposed measures include lowering barriers to deport refugees who do not receive asylum and creating an "early warning system" to detect radicalization among migrants.

Angela Merkel also said that the extremists wanted to reduce the country's readiness to accept refugees.

"The terrorists want to make us lose sight of what is important to us, break down our cohesion and sense of community as well as inhibiting our way of life, our openness and our willingness to take in people who are in need," she said.