Norway’s domestic security agency has warned about the possibility of a terror attack from rightwing extremists “in the coming year”.

In a statement, the PST said its heightened assessment stemmed from the fact that several Norwegian rightwing extremists had recently expressed support for the perpetrators behind attacks in New Zealand, the US and the failed attack in the Norwegian capital Oslo last month.

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On 10 August, Philip Manshaus allegedly stormed an Oslo mosque with guns before being overpowered. Several shots were fired and one person was slightly injured, but the suspect was held down by others in the mosque. The suspect has also been linked to the death of his stepsister.

The attack is believed to have been inspired by similar incidents this year in New Zealand and the US. In Christchurch, 51 people were killed in a mass shooting at two mosques on 15 March, while in El Paso, Texas, a gunman left at least 22 dead on 3 August.

The PST agency said “meeting places for Muslims and non-western immigrants”, political parties or persons, Jews and LGBT communities were “symbolic targets”.

The service updated its assessment hours after it said a Norwegian citizen in his 20s had been arrested for “terrorist association” on Thursday afternoon. It was not known whether that case was linked to the heightened assessment.

After last month’s failed attack, the PST said it had received a “vague” tip a year ago about Manshaus but it was not able to act because nothing concrete was revealed. The agency’s boss, Hans Sverre Sjoevold, said at the time there was no reason to change the overall threat assessment for Norway.