Britain and US fear Russia could be setting stage to use chemical weapons

Britain and the US fear Russia could be setting the stage to use a chemical weapon in Ukraine after Kremlin officials alleged without firm evidence that the US had been supporting a bioweapons programme in the country.

Earlier on Wednesday, Russian foreign ministry spokeswoman Maria Zakharova said Russia had documents showing evidence that the US had supported a bioweapons programme in Ukraine, involving plague, cholera and anthrax. Washington and Kyiv both denied the claims.

Such high-profile warnings from the west are as much designed to have a deterrent effect as they are based on any assessment that such weapons will actually be used.

But Russia has shown an apparent willingness to target civilians in Ukrainian cities such as Kharkiv and Mariupol, as its initial invasion was slow in making progress.

Direct attacks on civilians or civilian infrastructure are considered war crimes. The development, production and stockpiling and use of chemical weapons is banned by an international treaty signed by 193 countries.

But the fact that the chemical weapons involved were delivered through airstrikes led the OPCW to conclude the Syrian air force was responsible.

But it remains unclear if Moscow can concentrate enough force to begin an attack on the capital, which before the war had a population of 3 million.