Russia's first Moon mission in 50 years has failed after its Luna-25 landing module crashed on the lunar surface.
The country's space agency Roscosmos said on Sunday that it had not received a signal from the lander.
It was scheduled to make a landing attempt on Monday at the lunar south pole, a region that has not been explored previously.
There was a problem with a manoeuvre carried out on Saturday, Roscosmos said.
“At about 14.57 Moscow time, communication with the Luna-25 was interrupted,” it said on Telegram.
“The measures taken on August 19 and 20 to search for the device and get into contact with it did not produce any results.
“According to the results of the preliminary analysis, due to the deviation of the actual parameters of the trajectory from the calculated ones, the device switched to an off-design orbit and ceased to exist as a result of a collision with the lunar surface.”
Roscosmos said further investigations would be carried out to determine the cause of the crash.
India's Chandrayaan-3 mission is going as planned, with the country's Vikram craft expected to attempt a soft landing on the Moon on August 23.
Only the US, the Soviet Union and China have carried out a soft lunar landing.
The manoeuvre has a success rate of less than a 50 per cent.
Because the Moon does not have an atmosphere, parachutes cannot be used to slow landers down during a landing attempt, as they are on Earth and Mars.
Instead, landers use propulsion systems to brake and adjust position to touch down gently.
Technical problems and the lunar terrain, including craters and rocks, can also pose challenges for space agencies.
Israel's attempted lunar landing in 2019 failed because of a technical glitch.
Japanese company ispace reported an unsuccessful Moon mission this year when its Hakuto-R lander, which was carrying the UAE's Rashid rover, crashed on the lunar surface.
The company blamed a software issue.