Two refugees responsible for terror attacks in Germany were in repeated contact with suspected Islamic State members, Spiegel reported.

The men responsible for a train attacks in Wuerzberg and suicide bombing in Ansbach exchanged messages with individuals using different telephone numbers, including some registered in Saudi Arabia, according to the German weekly which did not identifying its sources.

The 17-year-old Afghan refugee responsible for the train attack in Wuerzberg, named as Riaz Khan Ahmadzai, reportedly discussed the best method for carrying out an attack with his Isis handler, who suggested driving a car into a crowd.

Ahmadzai supposedly rejected the idea as he did not have a driver's license, and instead said he would carry out an attack on a train. Several people were seriously injured in the attack before Ahmadzai was shot dead by police.

Six days later, on 24 July, Syrian refugee Mohamed Daleel detonated a suicide bomb near a music festival in the Bavarian town of Ansbach, injuring several people.

According to the report Isis did not want Daleel to explode a suicide bomb. Instead they told him to detonate the bomb and film the aftermath, sending the footage to them. The communications suggest that they planned for Daleel to carry out further attacks.

With support dipping in the wake of the attacks, Chancellor Angela Merkel has refused to back down on her policy of welcoming refugees, declaring the attackers sought to "undermine our sense of community, our openness and our willingness to help people in need ... we firmly reject this".