BERLIN: German Chancellor Angela Merkel on Thursday rebuffed calls to reverse her welcoming stance toward refugees in the wake of a series of brutal attacks in the country.

Merkel, who interrupted a summer holiday to face the media in Berlin, said the four assaults within a week were "shocking, oppressive and depressing" but not a sign that authorities had lost control.

The German leader said the assailants "wanted to undermine our sense of community, our openness and our willingness to help people in need".

"We firmly reject this," she said at a wide-ranging news conference.

Merkel repeated her rallying cry from last year when she opened the borders to people fleeing war and persecution, many from Syria, which brought nearly 1.1 million migrants and refugees to the country in 2015.

"I am still convinced today that 'we can do it' -- it is our historic duty and this is a historic challenge in times of globalisation," she said.

"We have already achieved very, very much in the last 11 months."

Merkel was speaking after a axe rampage, a shooting spree, a knife attack and a suicide bombing stunned Germany, leaving 13 dead, including three assailants, and dozens wounded.

Three of the four attackers were asylum seekers, and two of the assaults were claimed by the Islamic State group.

Merkel said that she would not allow jihadists, following a series of deadly attacks in France, Belgium, Turkey and the US state of Florida as well as Germany, to keep her government from being guided by reason and compassion.

"Despite the great unease these events inspire, fear can't be the guide for political decisions," she said.

"It is my deep conviction that we cannot let our way of life be destroyed."

'Urgent action'

While the German political class has largely called for calm, opposition parties and rebels from Merkel's own conservative bloc have accused her of exposing the country to unacceptable risks without stricter controls on people let in.

"Islamist terrorism has unfortunately arrived in Bavaria," the state's interior minister Joachim Herrmann told reporters Thursday, renewing calls by his Christian Social Union party for an upper limit on the number of new asylum seekers.

"We are awaiting urgent action from the federal government and Europe -- now is the time to act."

The deadliest attack came on Friday when a German-Iranian teenager who was born and raised in Munich opened fire at a downtown shopping mall, killing nine people before turning the gun on himself.

He had been under psychiatric treatment and investigators say he was obsessed with mass shootings, including Norwegian rightwing fanatic Anders Behring Breivik's 2011 massacre.

They have ruled out an Islamist motive, saying the assailant had far-right "sympathies".

On July 18, an asylum seeker from Afghanistan or Pakistan slashed train passengers and a passer-by with an axe and a knife in Wuerzburg before being shot by police.

And on Sunday, a failed Syrian asylum seeker blew himself up outside a music festival in Ansbach, wounding 15 people at a nearby cafe after being turned away from the packed open-air venue. IS claimed both attacks.

Already steeped in grief and shock, Germans were further rattled by news that a Syrian refugee had killed a 45-year-old Polish woman with a large kebab knife at a snack bar in the southwestern city of Reutlingen Sunday in what authorities called a personal dispute.

"Taboos of civilisation are being broken," Merkel said. "These acts happened in places where any of us could have been."

Looming elections

The German attacks came with two state elections looming in September, in Berlin and in Merkel's fiefdom of Mecklenburg-Western Pomerania, an economically depressed state on the Baltic coast.

The rightwing populist Alternative for Germany (AfD) party hopes to make a particularly strong showing there with a campaign against "Islamisation", which would deal Merkel a stinging blow one year ahead of a general election.

Merkel's popularity had suffered earlier this year, following a rash of sexual assaults in the western city of Cologne on New Year's Eve blamed mainly on Arab and North African men.

But her poll ratings had recently recovered as the refugee influx has slowed dramatically due to the closure of the Balkan migrant route and an EU deal with Turkey to stem the flow.

Analysts are awaiting new data to see what impact the recent attacks have had on her support.