The Polish authorities announced the arrest of four individuals in connection with sending "packages containing disguised explosives," allegedly shipped via courier companies to countries, including the United Kingdom.

The British news agency "PA Media" reported today, Tuesday, that the National Prosecutor's Office in Poland stated that the arrests are linked to sending packages that "ignited spontaneously or exploded" during land and air transport to EU countries and the United Kingdom.

The Polish Prosecutor's Office pointed out that authorities are working to trace the source of these packages, which were ultimately intended to be sent to the United States and Canada.

Reports indicated that the counter-terrorism police are investigating the possibility of Russian spies planting a bomb in one of the packages, which caught fire in a delivery warehouse after arriving by air in Britain.

News reports state that fire crews and staff dealt with a fire that broke out in a warehouse of "DHL" in Minworth, near Birmingham, on July 22nd.

It is believed that the package, which was supposed to contain an incendiary device, arrived at the "DHL" warehouse by air, but further details about the aircraft and its route have not been disclosed.

On Monday evening, the counter-terrorism police clarified that the arrests announced by Polish authorities are not related to their current investigations.