A SpaceX capsule tasked with bringing two stranded US astronauts back to Earth docked at the International Space Station (ISS) in the early hours of Sunday.

Butch Wilmore and Suni Williams have been on duty at the ISS for the past nine months following a series of technical failures with Boeing's Starliner spacecraft, which unexpectedly extended their eight-day trip.

NASA and SpaceX said the capsule docked at the ISS at 0404 GMT. A live-streamed video of the process showed the spacecraft attaching itself to the station's hatch.

Shortly after 0545 GMT, the newcomers were shown entering the zero gravity space station and hugging their counterparts.  

Plan to bring Butch and Suni back

On Friday, a SpaceX Falcon 9 rocket propelled the Dragon spacecraft into orbit with four astronauts — NASA's Anne McClain and Nichole Ayers, Japan Aerospace Exploration Agency astronaut Takuya Onishi and Roscosmos cosmonaut Kirill Peskov.

Wilmore and Williams, along with NASA's Nick Hague and Russia's Aleksandr Gorbunov, will overlap with the newcomers for a few days before leaving for Earth as early as Wednesday.

Williams and Wilmore's stay at the ISS has been lengthened by a series of technical issues and scheduling delays. The mission to bring them back turned political when US President Donald Trump called for them to be brought back earlier than planned, blaming Joe Biden's administration for abandoning them.

Both Williams and Wilmore have said they agreed with NASA's decision to turn their short trip into a general rotation which generally lasts six months.

Edited by: Kieran Burke