The Arab world's first space mission by a female astronaut has been put on hold, less than a week before the historic event was scheduled.
Rayyanah Barnawi and fellow Saudi astronaut Ali Al Qarni were due to blast off to the International Space Centre from the Kennedy Space Centre in Florida on May 9, at 6.43am UAE time.
The ISS on Wednesday issued a statement confirming it was "no longer targeting opportunities in early May" for the milestone journey.
It said Nasa, SpaceX and Axiom Space, the company in Houston that has helped arrange the trip for Saudi Arabia, were working to pinpoint a new date.
"Nasa, Axiom Space and SpaceX are working together to identify the best available opportunity to launch the Axiom Mission 2 to the International Space Station," the ISS said in a message released on Twitter.
"We are no longer targeting opportunities in early May. More information on the updated target launch date will be shared soon."
No reason has been given for the postponement.
Axiom Space confirmed the delay in its own post on social media and said the crew remained ready for its mission.
The Saudi space travellers are to be joined on the planned 10-day mission by former Nasa astronaut Peggy Whitson, as commander, and pilot John Shoffner.
They are scheduled to join Emirati astronaut Sultan Al Neyadi on board the orbiting space laboratory.
Dr Al Neyadi arrived on the ISS on March 3 for a six-month stint, the first such long-duration mission undertaken by an Arab astronaut.
Mishaal Ashemimry, who leads microgravity research at the Saudi Space Commission, previously said this would be the first flight under the kingdom's sustainable human space flight programme that was announced in September.
Saudi Arabia sent the first Arab into space in 1985 when Prince Sultan bin Salman took off on a space shuttle for a seven-day trip, but no long-term exploration programme followed.
“This is a significant milestone for us in the kingdom as we launch our first female and our second male to space,” Ms Ashemimry said.
“We're excited about this mission because it's an inaugural mission of our human space flight programme."
Twenty science experiments had been assigned to the AX-2 crew and the Saudi astronauts are expected focus on 11 that have been presented to them by universities in the kingdom.