A Chinese icebreaker that was en route to rescue a ship trapped in Antarctic ice was forced to turn back on Saturday after being unable to push its way through the heavy sea ice.

The Snow Dragon icebreaker came within 7 miles of the Russian ship MV Akademik Shokalskiy, which has been stuck since Christmas Eve, but had to retreat after the ice became too thick, said expedition spokesman Alvin Stone.

The Akademik Shokalskiy, which has been on a research expedition to Antarctica, got stuck Tuesday after a blizzard's whipping winds pushed the sea ice around the ship, freezing it in place. The ship wasn't in danger of sinking, and there are weeks' worth of supplies for the 74 scientists, tourists, and crew on board, but the vessel cannot move. - AP