Officers seized the eggs along with some 300 dead birds, some of which were stuffed and some frozen from a man resident in Österbotten in central Finland.
Police believe that crimes have been committed over a number of years and across several countries in the Nordic region.
“We suspect that this has occurred in Sweden too,” said Lars Lundman at Norrbotten police in northern Sweden to the TT news agency.
Most of the eggs seized were from endangered species and many would be expected to net substantial sums from rare egg collectors.
The arrest came as a result of Finnish police having received a tip from their Swedish counterparts, according to information from the Swedish Ornithological Society (Svensk Ornitologiska Förening – SOF).
The society referred to ongoing police investigations in Sweden concerning three suspects.
A Swedish prosecutor specialized in environmental law was present at the press conference in Finland and while Finnish police were unwilling to comment further on the Swedish angle, it has been widely reported.
The Swedish police investigations are reported to concern serious hunting violations and involve three suspected egg thieves operating in different parts of the country.
One of the three is also suspected of illegally purchasing, selling or exchanging eggs.
The suspected offences carry a range of penalties extending to prison sentences.
As a result of the spate of egg thefts, the counties of Västerbotten and Jämtland have decided to impose a temporary nature reserve in Stekenjokk mountains in northern Sweden.
The public have been excluded from the area for the month of June, the breeding season for the birds. The ban is being imposed with the help of the police.