The Danish Intelligence Agency PET said that three of the four men it arrested were Swedish residents who entered the country on Tuesday night.

It identified them as a 44-year-old Tunisian citizen, a 29-year-old Lebanese-born man and a 30-year-old Swedish resident whose origin was not immediately known.

The fourth suspect was a 26-year-old Iraqi asylum seeker living in Copenhagen, while the man arrested in Stockholm was described as a 37-year-old Swede of Tunisian background.

Jacob Scharf, head of PET, said that the arrests had stopped “an imminent terror attack”, adding that the suspects had allegedly planned to “kill as many people as possible”.