A Syrian refugee arrested in Germany after explosives were found in a flat in the city of Chemnitz was planning an attack on an airport in Berlin, according to intelligence services.

“We had clues from intelligence gathering that at first he wanted to attack trains in Germany,” Hans-Georg Maassen, head of Germany’s domestic intelligence agency BfV, tells state broadcaster ARD.

“In the end the plan became more concrete to attack airports in Berlin,” Massen says.

The BfV received a tip at the beginning of September that the Islamic State extremist group was planning a terrorist attack on infrastructure in Germany, Massen tells the broadcaster.

Jaber al-Bakr, 22, was arrested in the eastern city of Chemnitz after explosives were found in a flat.

Germany’s interior minister Thomas de Maiziere claimed al-Bakr was planning to carry out attacks similar in scale to those in Brussels in March and in Paris last year.

“According to what we know, the preparations in Chemnitz are similar to the preparations for the attacks in Paris and Brussels,” Thomas de Maiziere said in a statement on Monday

Joerg Michaelis, president of the Saxony state criminal investigation office, separately told a news conference that the 22-year-old refugee was most likely inspired by Islamic State.

“The behavior of the suspect speaks for an IS (Islamic State) context,” he said.

Islamic State gunmen and bombers killed some 130 people in the French capital in November and the militant group claimed responsibility for suicide bomb attacks in the Belgian capital four months later that left at least 30 people dead.