The hole discovered in the International Space Station (ISS) was drilled deliberately, the Russian space agency has said.

Last week mission controllers in Houston and Moscow noticed a drop in pressure on the station and astronauts discovered a hole in a Russian domestic module.

Although the leak was small enough to be fixed by the crew, if it had not been spotted the astronauts would have run out of air in 18 days.

Space debris or a micro-meteorite was initially blamed for the damage, but new pictures show the hole had been deliberately drilled and the Russian Space Agency Roscosmos and module manufacturer RSC Energia have launched an investigation to find the culprit.

One Russian politician and former cosmonaut has even claimed it could have been carried out by a homesick astronaut.

Speaking to Russia’s International News Agency RIA Novosti, Maxim Suraev said on-board sabotage by a mentally unstable crew member could not be ruled out.

“All of us are living people, everyone can want to go home, but this way is completely unworthy,” he said.