Washington’s ambassador to the UN, Linda Thomas-Greenfield, on Friday warned Russia’s claim that the US is funding “military biological activities” in Ukraine could be a pretext for Moscow launching its own biological weapons attack on Ukraine.

Thomas-Greenfield made the comments during a UN Security Council meeting that had been called at Russia’s request to discuss Moscow’s claims that Ukraine is secretly developing biological weapons with the help of the US.

As reported by the Guardian, the event saw some heated discussion.

The Russian ambassador to the UN, Vasily Nebenzya, evoked the terrifying specter of an “uncontrolled spread of bio agents from Ukraine” across Europe, but Thomas-Greenfield responded that Russia’s claim could be a pretext for launching its own biological weapons attack on Ukraine.

This came after the Russian ministry of foreign affairs posted a tweet last Sunday accusing the US and Ukrainian governments of running a secret “military-biological programme” inside the war-ravaged country.

Moscow claimed that its invading forces had discovered evidence of an “emergency clean-up” to hide the programme.

Moscow went on to claim that it had found documents related to the secret US operation in laboratories in the Ukrainian cities of Kharkiv and Poltava.

The Guardian reported that these allegations were quickly amplified by China, which supported the claims during Friday’s UN security council debate.

However, both the US and Ukraine have denied that they are developing any biological weapons inside the country.

At Friday’s meeting, Thomas-Greenfield, said: “I will say this once: ‘Ukraine does not have a biological weapons program.’” She went on to turn the accusation back on Moscow. “It is Russia that has long maintained a biological weapon program in violation of international law,” the Guardian reported.

The UN high commissioner for disarmament, Izumi Nakamitsu, confirmed that the UN was not aware of any biological weapons programmes in Ukraine.

However, the Guardian reported that Ukraine does operate biological laboratories which receive US funding.

The US undersecretary of state Victoria Nuland affirmed these facts in a Senate foreign relations committee hearing last week in which the Republican senator Marco Rubio asked her directly whether Ukraine had biological weapons, the Guardian reported.

Nuland did not answer the question directly but said: “Ukraine has biological research facilities.”

She also said there was concern that Russian forces were trying to gain control of the labs. “We are working with the Ukrainians on how they can prevent any of those research materials from falling into the hands of Russian forces.”

According to the Guardian, US funding to the laboratories had its roots in the fall of the Soviet Union after which money was pumped into Ukraine and other former Soviet countries to help them transfer scientific skills away from weapons programs towards public health initiatives.

The scheme was originally known as the Cooperative Threat Reduction (CTR) program, but is now more commonly referred to as the biological engagement program. It has been successful in supporting former Soviet and other countries to fulfil public health obligations, the Guardian reported.

“This is one of the best things that we do,” Dr Gigi Gronvall, senior scholar at Johns Hopkins Center for Health Security, told the Guardian.

Most of the work of the Ukraine labs today, Gronvall said, involved surveillance of diseases in animals and people as an early-warning system for illnesses such as African swine fever, which is endemic in the region. “We know pathogens don’t respect borders, so helping to put out public health fires before they become too big is an advantage to all of us,” she said.

However, the Guardian reported that as part of their work researching diseases the bio labs do seem to hold dangerous pathogens.

According to the report, the World Health Organization (WHO) is urging Ukraine to destroy any highly dangerous agents in its laboratories to avoid the risk of a disastrous outbreak should one of the labs come under Russian attack.

“As part of this work, WHO has strongly recommended to the ministry of health in Ukraine and other responsible bodies to destroy high-threat pathogens to prevent any potential spills,” the UN health agency said.

The WHO has worked in Ukraine for several years helping the bio labs improve their safety and security, so it knows what it is talking about, the Guardian reported.

However, the report stated that in addition to the threat of pathogens held in Ukrainian labs leaking out or falling into the hands of Russian forces, there is the threat of Russia potentially launching its own biological weapons attack.

The assessment of the US state department is that Russia continues to maintain an offensive biological weapons programme in violation of the convention that it has signed.

Earlier this week, the White House press secretary, Jen Psaki, accused Russia under Vladimir Putin of having a “long and well-documented track record” of using chemical weapons, pointing to the poisoning of the opposition leader Alexei Navalny and Russia’s support of the Syrian regime while it deployed chemical weapons.

She went on to warn that Moscow’s claim of a secret biological weapons programme in Ukraine could in fact be laying the foundations for a Russian chemical or biological weapons assault inside Ukraine, the Guardian reported.