A man in his forties has been arrested in connection with the investigation, reports newspaper VG.
At a press conference on Wednesday, police gave details of a major raid which resulted in the confiscation of 66 kilograms of amphetamine on the island of Tromsøya in October 2017. The seizure was one of the largest of its kind in northern Norway.
"The same day [as the raid], we detained a man in his forties who is a Serbian citizen," police spokesperson Einar Sparboe Lysnes said according to VG's report.
Investigation leader Yngve Myrvold said at the press meeting that he believes the seized drugs were intended for distribution in northern Norway.
"The confiscation is larger than anything we've had before. We characterise it as an enormous confiscation. This concerns us and confirms a negative trend we have seen," Myrvold said.
The man lived in Tromsø and had a temporary working visa at the time of his arrest, VG writes.
Police confirmed that they are working with law enforcement in Germany in connection with the investigation.
"We have a suspicion that there are more individuals involved in this and suspect that there are others connected to it with links to Germany," Lysnes said.
"We believe it is part of an international network," he added.
That man was not previously known to police and had not lived in Tromsø for a long period, reports VG.
No other arrests, in Norway or abroad, have so far been made in connection with the case.
The quantity seized in the October raid amounts to as much as 250,000 user doses, police said on Thursday.
"We are very pleased to have kept it away from the street," police said according to VG's report.
The Serbian citizen has been remanded in custody since his arrest and denies charges of gross narcotics-related offences, his defence lawyer Reidar Steinsvik told VG.