STOCKHOLM - Over 60 percent of ships involved in arms and drugs trafficking belong to companies in the European Union (EU), the North Atlantic Treaty Organization (NATO) or the Organization for Economic Cooperation and Development (OECD) countries, a study showed on Monday.

According to a report released by Stockholm International Peace Research Institute (SIPRI), among the ships related to illegal transfers of arms, drugs and sensitive materials which can be used in production of weapons of mass destruction in the past 20 years, 19.5 percent belong to commercial shipping lines based in Germany, which is on the top of the list, followed by Greece and the United States.

The co-author of the report Hugh Griffiths explained that the ship owner or the captain sometimes even had no idea about the drugs or arms hidden in legal cargoes.

Containers are used as ideal covers by smugglers, since only a small part of them would be inspected among countless containers passing through ports all over the world everyday, he said.

"Ship owners and even customs officers often just have to take it on trust that what's inside the container is what it says on the cargo documents," said Griffiths.

Meanwhile, in the cases that the ship owners, operators and captains are involved directly, the trafficking ships tend to be sailing under "flags of convenience" and seem to be shabby.

"This is an international phenomenon," said Griffiths, adding that on the basis of the current mechanisms, "the major players" in global shipping industry need to cooperate to fight against trafficking.