This article gives more info. The subject was raised by China. (And initially revolved around where covid started.)
During a routine press conference on Tuesday, the Chinese Foreign Ministry spokesperson mentioned the 26 bio-labs and other related facilities in Ukraine, under the absolute control of the US Department of Defense, as well as the US' 336 biological labs in 30 countries, asking "what is the true intention of the US?"
An agreement signed by the US Department of Defense and the Ministry of Health of Ukraine in 2005, was aimed to prevent bio-weapons and pathogens from being abused, and Ukraine seems to run those labs.
The agreement said that the US Department of Defense has the right to audit and examine materials, training of personnel and services provided in accordance with the agreement.
The most important part is that the agreement says that the Ministry of Health of Ukraine shall transfer to the US Department of Defense copies of dangerous pathogen strains collected in Ukraine.
US tries to refute 'rumors' about its bio-labs in Ukraine, but can we believe it? - Global Times