Russia has claimed that the U.S. developed a "synthetic coronavirus pathogen based on the omicron strain and the original 'Wuhan' variety."

"The modified virus acquired by the Americans killed 80% of infected model animals, causing abnormal neurological signs and significant lung damage."

"Antibody testing revealed an 11-fold decline in their capacity to neutralize the new virus, as well as the ineffectiveness of current vaccinations," Igor Kirillov, head of biological and chemical defense troops, said in a news conference on Saturday.

Kirillov claimed the modified virus was developed by Boston University.

He added that the U.S. continues its military biological activities in third countries, and prefers conducting experiments abroad because of the high risk of accidents.

Russia, he said, will demand the creation of an effective mechanism for monitoring such activities at the upcoming meeting of the Biological Weapons Convention.

In a separate statement, the ministry also said Moscow and Kyiv held another round of war prisoners exchange and as a result, nine Russian soldiers returned from captivity.