German police said on Tuesday they had detained a man in connection with a dangerous threat at the iconic Cologne Cathedral in the western state of North Rhine-Westphalia (NRW).

Police announced the arrest of five men after searching an apartment in Wesel, some 100 kilometers (approximately 62 miles) north of Cologne.

Four were later released, but a 30-year-old Tajik man remained in custody, with a court decision allowing his detention until January 7.

What do we know about the suspect?

Police said the man was taken into custody on Sunday evening. With little revealed about the detained man, police said they had obtained information that was relevant to state security.

"We are exhausting all legal possibilities to protect the people, the cathedral and the upcoming New Year's Eve celebrations," Cologne police chief Michael Esser said in a brief statement.

Sources told Germany's DPA news agency that the man was known to authorities in the neighboring state of Saarland.

Regional broadcaster WDR also reported that the suspect had previously been arrested in Saarland but was later released.

Authorities on alert

On Saturday, German police said they had received an alert that a group may be planning an attack on the Cologne Cathedral on New Year's Eve.

Security was ramped up outside the landmark building — which is the largest Gothic cathedral in northern Europe — attracting some 6 million visitors annually.

German authorities have repeatedly warned of potential terror threats, against the backdrop of the Israel-Hamas war and the repercussions beyond the Middle East region.

zc, rmt/kb (dpa, Reuters)