The launch of a Russian spacecraft to the International Space Station was aborted at the last minute on Thursday, according to a broadcast of the scheduled launch.
The Soyuz MS-25 was due to take off from the Baikonur space port in Kazakhstan on Thursday, carrying three astronauts from Russia, the United States and Belarus, but was cancelled just seconds before blast-off.
"Attention at the launch complex. There was an automatic launch cancellation. Bring the units of the launch complex to the initial state," the flight controller said in a live broadcast by Russia's space agency Roscosmos.
A separate NASA broadcast of the planned launch said it was aborted 20 seconds before take-off.
"This is Mission Control Houston. To recap: today's launch of Soyuz MS-25 was aborted at about the T minus 20 second mark. No reason has yet been given," the announcer said.
It said the "engine sequence start" did not occur as expected, triggering an "automatic command to abort the countdown".
"The crew is safe on board Soyuz MS-25. Work will now begin to extract the crew from the spacecraft and get them back to their crew quarters at the Cosmonaut Hotel," the NASA announcer said.
Beyond the "automatic" launch cancellation that was shown on the live broadcast, there was no immediate comment from Roscosmos on what caused the launch failure.
The mission was set to carry the first Belarusian astronaut, 33-year-old Marina Vasilevskaya, into space.
Space is one of the final areas of US-Russia cooperation amid an almost complete breakdown in relations between Moscow and Washington over the last two years.
Russia has said it plans to ditch the ISS and build its own space station.