Norwegian Justice Minister Tor Mikkel Wara is to leave his post temporarily after his partner was arrested on suspicion of setting fire to his car.
Laila Anita Bertheussen, 54, was detained by Norway’s PST security agency in the wake of five incidents at the minister’s home.
She is currently suspected only in the 10 March arson attack but will also be investigated over the other attacks.
Prime Minister Erna Solberg said it was a tragedy for Mr Wara and his family.
“This information came as a shock to me and to the entire government,” Ms Solberg told a dramatic news conference in Norway.
The prime minister was told about the arrest about an hour before police made the details public.
PST head Benedicte Bjornland said Ms Bertheussen, whom she described as the minister’s live-in partner, had been charged with carrying out an act that falsely indicated a crime had been committed.
She is unlikely to be kept in custody but could face a fine or a year in jail if found guilty.
The incidents targeting Mr Wara began 6 December when his house and car were daubed with the word “racist” in Norwegian.
Further attacks took place in January and February, with another two this month.
When the minister’s family car was set alight on Saturday night as it was parked outside their home in Oslo, Ms Solberg had condemned the incident as a threat against Norway’s “open and democratic society”.
The PST had come under fire for failing to solve the series of crimes, which the prime minister said had made many other politicians and their families anxious.
Although he belongs to the populist Progressive Party, Mr Wara is seen as a moderate politician.
His party leader said everyone including Mr Wara was in shock.