Police in the northwestern German city of Bremen said on Saturday that they had received information "from a federal authority" about "activities of potential Islamist offenders."

They said that "coordinated and appropriate security measures" were being taken to combat the threat of a terrorist attack, including in public spaces.

A police spokesman told the DPA news agency that all relevant buildings were being protected.

No further details were given.

Since the beginning of the year, German authorities have warned of the potential danger of attacks by radical Islamists on several occasions.

Roughly two weeks ago, police in the northern city of Braunschweig canceled a Carnival parade after receiving concrete information about possible attacks with an Islamist background, while on January 19, a demonstration by the "anti-Islamization" group PEGIDA was called off for similar reasons.

tj/kms (dpa, Reuters)