Roscosmos chief Oleg Ostapenko said on Wednesday the problem was in the ship's orientation system. The crew took off their spacesuits to prepare for the long flight, Ostapenko said in remarks carried by Russian news agencies.
Later Wednesday, NASA said in a press release that "initial information indicates the spacecraft was not at the proper attitude, or orientation, for the automated thruster." The space agency said Russia had confirmed that two maneuvers were completed to put the capsule on course.
Until last year, Russian spacecraft used to routinely travel two days to reach the orbiting laboratory. Wednesday would have been only the fifth time that a crew would have taken the six-hour "fast-track" route to the station.
The new crew will join Japan's Koichi Wakata, NASA's Rick Mastracchio and Russia's Mikhail Tyurin, who have been at the station since November. The new crew is scheduled to stay in orbit for six months.
NASA said the delay was not expected to change plans to launch a supply ship to the space station from Cape Canaveral, Fla., on Sunday night.
AP writer Vladimir Isachenkov contributed to this report.