(CNN) -- Finnish authorities have launched an investigation after impounding 69 Patriot missiles from a ship bound for China.
Police said they also found explosives and propelling charges aboard the British-flagged cargo ship Thor Liberty at the port of Kotka, about 75 miles east of Helsinki.
The Patriot is a surface-to-air missile system manufactured by the U.S. company Raytheon and has been sold to various nations.
The Thor Liberty sailed from Germany on December 13, police said. It was set to sail to Shanghai.
Finnish authorities found the defense materials during a customs search and are looking into whether export laws were violated.