A hole that caused an air leak and pressure drop at the International Space Station last week was caused by a man-made drill hole not a micrometeorite strike — and may even have been punctured deliberately as an act of sabotage, an investigation has found.

Astronauts successfully patched the two-millimetre hole with tape and sealant last Thursday morning after it had caused a small, non-hazardous pressure drop the night before. The hole was in the upper part of the docked Soyuz spacecraft, where it attaches to the space station, called the orbital module, NASA said.

Dimitry Rogozin, head of Russia's space agency Roscosmos, said Monday that the theory that the hole was caused by a micrometeorite impact has been ruled out, several media outlets, including Agence France-Presse, reported.

That's because the hole was made from the inside of the spacecraft, and appears to have been made by a drill.

The reports quote Rogozin's televised comments that there were several attempts at drilling, the drill had been held by a wavering or faltering hand, and there were traces of the drill sliding along the surface.

"What is this: a production defect or some premeditated actions?" asked Rogozin, quoted by Agence-France Presse. He added that Roscosmos isn't ruling out any theories, including "deliberate interference in space."

He added that it was "a matter of honour" that Rocket and Space Corporation Energia, which made the Soyuz, find the person responsible and determine whether the drill hole was an accident.

The incident is being investigated by a special commission involving RSC Energia, Roscosmos, and TsNIIMash, a Russian institute of space and rocket science, reports the Russian news agency RIA Novosti.

Meanwhile, the same news agency reported that a Russian federal politician, former cosmonaut Maxim Suraev, says he doesn't rule out the possibility that the hole was drilled by a "mentally unstable member of the ISS crew."

There are currently six crew aboard the space station: