Last month's drone alert issued in the Uusimaa region was triggered by a Ukrainian mistake, according to Helsingin Sanomat.
The newspaper on Monday reported that Ukraine warned Finnish authorities that drones involved in a large-scale attack on Russia had inadvertently been sent towards Finland.
After the incident, the Finnish Defence Forces told Yle that the alert was linked to a major Ukrainian drone operation against Russia.
The Defence Forces have not disclosed how they learned of the potential threat, nor have they provided further details about the nature of the risk.
Neither Finnish nor Ukrainian government officials provided comments on the matter to Helsingin Sanomat.
On 15 May, a drone alert affecting the Uusimaa region led to people being advised to move indoors and stay there. Some 1.8 million people live in this area, making it Finland's most populous.
Air traffic at Helsinki Airport was also temporarily suspended for a few hours as a result of the warning.
