Astronauts aboard the International Space Station have been told to prepare for urgent evacuation after an air leak.
The breach, which is understood to have worsened, was occurring on the Russian segment of the station.
All those aboard have been told to shelter in the spacecraft.
A Russian crew member was understood to be attempting to fix the air leak.
Nasa has confirmed the leak is taking place on a portion of the orbital laboratory.
The ISS is the largest human-made structure in space and an orbiting laboratory for scientific research.
The project is a collaborative project involving five space agencies.
Astronauts from the US, Russia, Europe, Japan, and Canada are on board.
Astronauts aboard the International Space Station have been told to prepare for urgent evacuation after an air leak
|GETTY
It circles the Earth at an average altitude of about 250 miles (400 km), travelling at roughly 17,500 mph (28,000 km/h).
This means it orbits the Earth once every 90 minutes.
The ISS's in-orbit construction began in 1998, and the station has been continuously occupied by humans since November 2000.
Over 280 individuals from 26 countries have visited the station, making it the longest-running example of continuous human presence in space.
International Space Station astronauts sent a photo of a mission patch floating on the station to support Artemis II | NASA/JESSICA MEIRTypically hosts a rotating crew of seven astronauts and cosmonauts.
Bethany Stevens, who serves as the Senior Advisor and Press Secretary for Nasa, said: "The Zvezda service module transfer tunnel, known as PrK, has suffered from cracks and leaks for some time, and has been mitigated by Roscosmos as much as possible to date."
The spokeswoman added that the cracks "have always been a concern" and that Nasa has monitored them closely.
They have worked with their Russian cosmonauts to "determine the root cause of the cracks".
The International Space Station this means it orbits the Earth once every 90 minutes
| GETTYShe added: "Following new leaks, Roscosmos has elected to proceed with a more extensive repair operation on Friday, June 5.
"Out of an abundance of caution, NASA has directed all four of the agency's SpaceX Crew-12 members and NASA astronaut Chris Williams to assume an elevated safety posture in the Dragon spacecraft while the repair is underway.
"We continue to work with our Russian counterparts, along with the rest of the international community that supports the space station, to arrive at a more permanent resolution."
The station is currently scheduled to be safely deorbited in 2031.
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