Häme police said that they recovered 34 packages containing narcotic substances during a series of checks on a mail distribution centre in Lahti.
Officers originally confiscated 41 packages, but 34 contained illegal substances. The find included small quantities of marijuana as well as 150 pills containing substances classified as medication in packets containing between two and 15 tablets per packet.
The intended recipients of the packages are now suspected of offences relating to using illegal drugs. However the senders are suspected of offences relating to their attempts to sell the illegal substances.
Häme police said that raid on the mail sorting centre followed information that the unit received about drugs being trafficked via mail. The officers used a sniffer dog, Jekku, to help track down the illicit packages.
"We occasionally conduct checks when there is reason to suspect that drugs are on the move," said Detective Inspector Jari Kiiskinen.
Police are currently investigating the identities of the senders and recipients of the packages.