Norway on Sunday revised downwards the risk of a terrorist attack by militants coming from Syria, three days after stepping up security to face a threat it deemed "credible" and imminent.
"Based upon the work carried out these last days, we can say that the threat of a terrorist attack against Norway has somewhat decreased," Norway's intelligence service (PST) chief Benedicte Bjoernland said at a press conference.
"But the situation is still serious and hasn't been clarified yet."
The PST declined to reveal the reasons behind its new assessment, explaining only that it was supported by information obtained in Norway and abroad.
On Thursday, PST said it had "recently received information that a group of extremists from Syria may be planning a terrorist attack" in the country.
The threat was deemed "credible" but "non-specific".
The eventual target, the timing of the attack, the identity of the militants and their location were not known, PST said.
Norway will keep tightened security measures "until further notice", police head Odd Reidar Humlegaard said on Sunday.
Norway has increased border controls and armed police presence in stations and airport, recalled officers from leave and closed several public buildings to the public.
The country's Jewish museums are also closed.
On May 24, an individual killed four people after opening fire against the Jewish Museum in Brussels.
The suspected perpetrator is French-Algerian Mehdi Nemmouche, who has spent more than a year in Syria, where he is thought to have joined some of the most violent and radical jihadist groups.
According to PST, some fifty people with links to Norway have travelled to Syria to fight in the conflict and about half of them have returned to the Nordic country.
The return of these radicalised militants to Europe and North America has become a major concern for Western intelligence services.
In a report from last December, the London-based International Centre for the Study of Radicalisation (ICSR) said the number of foreign fighters in Syria had almost doubled since last year, to up to 11,000 from 74 countries.