A suitcase exploded near a reception centre for migrants in southern Germany, but the blast may have been caused by an aerosol can inside it, and there was no evidence of explosives being involved, police said.

The incident in the Bavarian town of Zirndorf, happened at around 2.15pm local time, sparked jitters following the spate of violent attacks since 18 July 18 and news of the blast spread rapidly on social media outlets. 

So-called Islamic State has claimed responsibility for two of the five attacks.

"Up to now, there is no evidence that the suitcase was detonated by explosives," a police statement statement. "At no point were any people in danger."

A spray can in the suitcase may have triggered the explosion, causing the suitcase to burst into flames, police said.

Police said they were looking for a man around 30 years of age and a woman of about 25 who may have owned the suitcase.

The incident happened in Bavaria, where authorities are on edge after three attacks in a one-week period.

On Sunday, a Syrian asylum seeker with suspected links to the so-called Islamic State group blew himself up near a music festival in Ansbach, wounding 15 people.

Nine people were killed in a shopping centre shooting spree in Munich on Friday, just six days after four passengers on a train and a passer-by were wounded in an axe attack in Wuerzburg.

No evidence Algerian on run in Germany has ties to Islamic State - police

Meanwhile, police said an Algerian suspect missing in Bremen, Germany, had made statements sympathising with a gunman who killed nine people in Munich, and with so-called Islamic State, but they had no evidence he had any concrete plans or ties to the militant group. 

The 19-year-old man made the comments while in police custody in the state of Lower Saxony this past weekend for several thefts, a spokesman said.

He was transferred to a psychiatric facility after he tried to hurt himself multiple times and authorities determined he had consumed drugs and posed a possible danger to himself and others, the spokesman said.

The man fled that facility earlier today, yelling, "I'll blow you up."