AMSTERDAM - A small Dutch freighter sank early Tuesday morning after colliding with a tanker in the North Sea off the Belgian coast, the Netherlands’ coast guard said. All aboard were rescued. Coast Guard spokeswoman Vanessa Strijbosch said 11 of the 12 crew of the Dutch freighter Flinterstar were rescued from frigid North Sea waters, and one was being treated for hypothermia. The 12th was still aboard. The Marshall Island-flagged tanker Al-Oraiq also suffered damage in the collision, which occurred 10 kilometres from the coast near the Belgian port of Zeebrugge, she said. According to a statement by Belgian gas transmission operator Fluxys, the Al-Oraiq took on a little water but has been towed to Zeebrugge. The ship, which carries liquefied natural gas, did not leak any petrochemicals. Traders said there was no immediate effect on Belgian wholesale gas prices. Dutch media reported a cleanup operation is underway for oil leaking from the tanks of the Flinterstar, which had been carrying steel plates destined for Spain. The coast guard published photos of the submerged ship resting awkwardly on a sandbank, its foredeck protruding up out of the water. Traffic was kept for several hours from entering or exiting the Western Schelt estuary, an important shipping route to the port Antwerp. The rescue operation, which included at least three rescue ships, five tug boats and a helicopter, was led and coordinated by the Belgian coast guard, with assistance from the Dutch. The cause of the collision is not yet known. (Reporting by Toby Sterling; Editing by Shri Navaratnam, Larry King)