The United Nations on Friday said it had no evidence Ukraine had a biological weapons program while Washington and its allies accused Russia of spreading the unproven claim as a possible prelude to launching its own biological or chemical attacks.

Russian forces inched towards Kyiv and pounded civilian areas in other Ukrainian cities Friday (11 March), drawing warnings of "unimaginable tragedy" as the United States and the EU moved to tighten the economic noose around the Kremlin.