German police have arrested two Algerians they suspect of having links to Islamic State, as the city of Cologne kicks off its annual Carnival celebration.
Reports said the two suspects were arrested Thursday during searches in the capital, Berlin, and in other regions.
The men are suspected of planning an attack "threatening the security of the state," according to police. Authorities are searching for two other men in connection with the plot.
The arrests come as the city of Cologne begins a huge Carnival celebration that precedes the beginning of Lent. After a shocking string of sexual assaults that occurred in Cologne during New Year's celebrations, police are on alert to prevent a repeat of the incidents.
The carnival festivities include street parties, song and dance, and alcohol consumption by revellers in fancy dress. The carnival runs until Ash Wednesday on February 10.
German authorities are determined to be out in force.
Police have doubled the number of officers on hand compared with last year to more than 2,000, and are also bringing in 350 cadets.