Russia's space agency says an unmanned supply ship bound for the International Space Station has failed to reach its planned orbit, AP reported. The brief statement from the Roscosmos agency did not specify whether the Progress supply ship that was launched Wednesday from the Baikonur cosmodrome had been entirely lost. Agency officials could not immediately be reached for comment by The Associated Press. The statement said the third stage of the rocket firing the ship into space had failed at 325 seconds into the launch. The ship was carrying more than 2.5 tons of supplies, including oxygen, food and fuel. Since the ending of the U.S. space shuttle program this summer, Russian spaceships are the only supply link to the space station. There are six astronauts aboard the International Space Station, which orbits 350 kilometers (220 miles) above the Earth. They are Russians Andrei Borisenko, Alexander Samokuyayev and Sergei Volkov, Americans Michael Fossum and Ronald Garan and Satoshi Furukawa of Japan. The Interfax news agency cited a Russian space analyst, Sergei Puzanov, as saying the space station had supplies already aboard that could last two to three months and "the situation with the loss of the Progress cannot be called critical." In July of 2010, a Progress supply ship failed in its first automatic docking attempt due to equipment malfunction, but was connected with the orbiting laboratory two days later.