BERLIN (Reuters) - Some 450 German special commandos made 12 co-ordinated raids on Thursday and arrested two men suspected of planning an imminent Islamist attack, police said.

Guns, munitions and a machete were recovered in the swoop launched on the basis of indications of a “possible concrete impending terrorist attack” by Salafists, ultra-conservative Islamists, mostly in the university town of Goettingen.

No concrete plans of a targeted attack or evidence of links to Islamic State were found.

“We came to the conclusion that there was an imminent danger that had to be averted,” Goettingen police chief Uwe Luehrig told a news conference.

The men arrested were a 27-year-old Algerian and a 23-year-old Nigerian. Both were born in Germany and were neither refugees nor seeking asylum.

“It was quite clearly a dangerous situation,” Luehrig said. “They had weapons and munitions. They could have staged the attack at any moment.”

Germany’s BND foreign intelligence agency was one of several security agencies that collaborated in the raids, he said.

The Federal Prosecutor’s office also said on Thursday that it had earlier this month charged three Syrian men, aged 18, 19 and 26, of having joined Islamic State in the Syrian city of Raqqa.

It said the three were send by the militant group with the possible goal of carrying out an attack in Germany. They had applied for asylum upon arrival in 2015 and were arrested in September last year.

Germany has been on high alert and there have been numerous police raids, especially since an Islamic State-inspired attack by a Tunisian refugee on a Christmas market in Berlin that killed 12 people in December.

On Wednesday, a 36-year-old Tunisian asylum seeker was arrested on suspicion of planning an Islamist attack. He was also wanted in his homeland over the deadly 2015 attack on the Bardo Museum in Tunis.