A Norwegian teenager detained after the killing of an Ethiopian-origin worker at an Oslo hostel also planned an attack on a mosque, police said on Thursday.

The 18-year-old was arrested after the killing on Saturday night of Tamima Nibras Juhar, a 34-year-old social worker, at the Oslo hostel where she was a staff member and the suspect was a resident.

The youth is now the subject of a murder and terrorism enquiry after police said he had expressed “opinions hostile to Muslim people”.

The suspect “declared that he had the intention of committing an attack against a mosque at Hoenefoss”, a town about 60 kilometres (40 miles) north of the Norwegian capital, police said in a statement.

“It is important to stress that there are still many indications that the suspect’s capacity to carry out further attacks was limited,” police added.

The youth was said to have acted alone.

He has been identified by media as German national Djordje Wilms, who moved to Norway from Serbia as a child, although police have not confirmed these elements. Norway has been marked by extreme-right-wing attacks in recent years.

In 2011, neo-Nazi Anders Behring Breivik killed 77 people by setting off a bomb in Oslo and then opening fire at a youth festival on the island of Utoya.

In 2019, Philip Manshaus opened fire in a mosque in the Oslo region before being overcome.