Boeing's Starliner spacecraft has undocked from the International Space Station and begun its return to Earth without crewmembers.

The Starliner was separated from the ISS shortly after 22:00 UTC on Friday.

The spacecraft will use its thrusters to gradually lower its orbit and reenter the Earth's atmosphere. It is expected to return to Earth at around 4:00 UTC on Saturday.

The spacecraft lifted off in June with two US space agency NASA astronauts onboard for a test flight to the ISS.

It was initially scheduled to bring them back to Earth after about a week. But the glitches found in its thruster system forced it to remain at the ISS.

Last month, NASA decided that the Starliner would return to Earth without the two astronauts for safety reasons.

Starliner was originally expected to be a new means to travel between the ISS and Earth, if approved by NASA after the test flight. But the glitches, and change in plans, make the future uncertain.

The two astronauts are now expected to return in February next year on a different spacecraft.