Swedish customs and police confiscated a large amount of drugs from the group after working together with law enforcement officials in seven other European countries.
Police had been monitoring the group for some time and knew the shipment was crossing into Sweden. Seven were ordered to be detained by a court on Sunday, but one was released due to lack of evidence.
The six in custody have roots in the former Yugoslavia. Sweden worked with officials in Serbia, Croatia, Slovenia, Austria, Germany and Denmark to make the arrests, TT said.
“It is seldom that cooperation works as well as it has this time,” said Karl Gunnheden, spokesman for Swedish customs. “We have followed this group for several months.”
Police did not comment on the type and amount of drugs confiscated or on which charges the suspects will face in court, TT said.