Russia's space agency on Tuesday said that the crew stuck on the International Space Station because of a damaged capsule were now expected to return to Earth in September, a year after they first launched into orbit.
Russian cosmonauts Dmitry Petelin and Sergei Prokopyev and NASA astronaut Frank Rubio flew to the ISS in September 2022 aboard a Soyuz MS-22 capsule.
They were scheduled to return home in the same spacecraft, but it began leaking coolant in mid-December after being hit by what US and Russian space officials believe was a tiny space rock.
Russia plans to send a rescue ship, a Soyuz MS-23, on February 24.
Before the leak, the trio had been due to return to Earth on March 28, 2023.
But on Tuesday, Russia's Roscosmos space agency said in a statement that their return "at the moment is scheduled to take place aboard the Soyuz MS-23 in September, 2023."
Roscosmos said the extended space stay -- normally ISS missions last six months -- posed no health risks for the crew, adding that they had taken the news of their mission extending "positively."
In 2021, Russia's Pyotr Dubrov and the US's Mark Vande also spent a year on the ISS after their mission was extended, it said.
The launch of the rescue Soyuz capsule was itself postponed earlier this month after another vessel -- a Russian supply ship docked at the ISS, the Progress MS-21 -- had also leaked coolant, sparking concern.
On Tuesday Roscosmos said that particular leak was caused by an "exterior impact," based on photos and videos that showed holes on the capsule's exterior, including on the radiator and solar panels.
Space has remained a rare venue of cooperation between Moscow and Washington since the start of the Russian offensive in Ukraine and ensuing Western sanctions on Russia.
The ISS was launched in 1998 at a time of increased US-Russia cooperation following the Cold War "Space Race."
Russia has been using the ageing but reliable Soyuz capsules to ferry astronauts into space since the 1960s.
But in recent years Russia's space programme has been beset by a litany of problems which have led to the loss of satellites and vehicles.