Nearly four times as many drugs were seized at Ireland's mail centres last year compared to 2018.
Another €1.4 million worth of substances were recovered in the first four months of this year.
These new figures have been released to Newstalk by Revenue under the Freedom of Information Act.
They show a dramatic increase in the value of drugs seized at An Post's mail four centres - Athlone, Portlaoise, Cork and Dublin.
In 2018, €2.6 million of seizures were made, but this rose to over €9.7 million last year.
By far the largest amount last year was in Portlaoise Mail Centre, which accounted for nearly €8 million worth of seizures.
They include 13,500 tablets and 403 kilos of drugs.
Security analyst Declan Power believes there's a number of reasons for the increase.
He said: "The increase might indicate you now have smaller criminal groups maybe trying to bring in prescription drugs or other drugs of that nature for sale.
"It also perhaps indicates there's a greater awareness by law enforcement, and that their levels of investigation, detection and apprehension have increased."
In the first four months of this year, almost €1.4 million worth of seizures were made - nearly half of which were in Dublin mail centre.
