NATO intelligence estimates that for every Ukrainian soldier killed defending Bakhmut, Russian forces have lost at least five, a military official with the North Atlantic alliance told CNN on Monday, Report informs.

The official cautioned the five to one ratio was an informed estimate based on intelligence.

The official spoke to CNN on the condition they remain anonymous because they are not allowed to discuss this intelligence. Despite the favorable ratio, they also said Ukraine was suffering significant losses defending the city.

Ukrainian officials have repeatedly claimed they were inflicting heavy losses on Russia as Moscow tried to take Bakhmut.