Three Ukrainian soldiers have died and nine were wounded during a training accident on July 6, the Ukrainian military said in a statement.
The soldiers were killed by a suspected mortar explosion during tactical exercises, the statement added.
It said that there would be an official investigation.
The accident happened in western Ukraine.
Kyiv is fighting a Russia-backed separatist insurgency in the country’s east that has killed at least 10,300 people since 2014.