Norway's parliament, the Storting, was temporarily closed off Wednesday after repeated threats against the institution, police said.

Two threats were directed at the institution on Tuesday, but no link between them has been established yet, Oslo police chief of operations Sven Bjelland told a press briefing.

The first was not deemed credible, but the second threat led police to cordon off the building in the centre of Oslo on Wednesday.

According to Norwegian media, the threats were bomb threats, but police did not confirm this.

The public was asked to leave the building, but work continued normally inside in the morning.

"We are now at a stage where we do not believe that these (threats) were real, but that does not mean that they are not serious," Bjelland told reporters after noon Wednesday.

The security perimeter set up around the parliament building was therefore lifted, but police said that they would maintain a presence on site.

Police gave no further details about the threats or their motives but said the source of the first threat had been identified.

Images and video from the scene showed heavily-armed police officers wearing helmets surrounding the building, while police dogs were used to inspect the surrounding area.

In Norway, police are generally not armed, but they had been authorised to be temporarily armed from March 27 to April 2 -- during Easter -- without authorities changing their threat assessment level, which is currently considered "moderate".