The spokesman said the Progress craft could not complete the docking procedure, possibly because part of the docking system malfunctioned and got in the way.
"The structural integrity of the spacecraft and the space station was not affected," he said, adding there was no immediate threat to the crew on board the station.
"We are not receiving data transmission from the Progress at this point," the spokesman said.
He said the mission control will receive an update on the situation in about 40 minutes when the space station enters the zone of radio coverage.
The spokesman said the crew may have to conduct a space walk to deal with the situation, but it would happen only after a thorough analysis of the incident, which might take several days.
Mission Control is also considering undocking the cargo vehicle in order to repeat the docking procedure, the source said.
The Russian rocket and space corporation Energiya later confirmed that the unsuccessful docking was apparently caused by the failure of an antenna of the Kurs auto-docking system on board the cargo vehicle to fold in.
