Polish authorities say four people have been charged in an alleged plan to send explosives via courier service to Canada and the United States.
The RCMP says it is aware of the arrests, but declined further comment to preserve the integrity of the investigation.
The Polish group’s alleged activities apparently involved sending camouflaged explosives to other European countries, with the eventual aim of targeting North America.
Poland’s national prosecutor’s office says efforts are underway to identify other possible suspects.
The Polish probe began in August based on security information and is being conducted in co-operation with that country’s civil-aviation authority.
Poland’s embassy in Ottawa did not immediately respond to a request for information.