The International Space Station crew on Thursday was repairing a small "leak" most likely caused by a collision with a small meteorite, the head of the Russian space agency said, adding the incident presented no danger.

"Overnight and in the morning there was an abnormal situation -- a pressure drop, an oxygen leak at the station," Roscosmos chief Dmitry Rogozin was quoted as saying by Russian news agencies.

"A micro fracture was found, most likely it is damage from the outside. The design engineers believe it is the result of a micrometeorite," he said.

He said the fracture was found on the Soyuz ship that brought astronauts to the ISS in June for a six-month mission and is currently docked with the space station. The fracture will be patched from the inside, he said.

NASA confirmed the problem, saying it consisted of a "minute pressure leak" and that the crew was repairing it.

"The leak has been isolated to a hole about two millimeters in diameter" and slowed through application of thermo resistant tape, but a more permanent solution was in development.

NASA and Russian space officials stressed Thursday that the six astronauts are in no danger.

The leaking Soyuz — one of two up there — arrived at the orbiting lab in June with three astronauts. It's their ride home, too, come December, and also serves as a lifeboat in case of an emergency.

A NASA spokesman said it was premature to speculate on whether the three might have to return to Earth early if the leak, even as small as it is, cannot be stopped.

The hole is located in the upper section of the Soyuz, which does not return to Earth, according to NASA.

The 250-mile-high outpost is home to three Americans, two Russians and one German. Orbital debris is a constant threat to spacecraft, even the tiniest specks