Russia has vetoed a UN resolution condemning the reported use of chemical weapons in Syria and urging a speedy investigation.
The resolution, which aimed to bolster support for international inquiries into a deadly toxic gas attack in Khan Sheikhoun last week, was being pushed by the US, Britain and France.
While 10 nations voted in favour, Russia and Bolivia vetoed the resolution, while China, Kazakhstan and Ethiopia abstained.
It marks the eighth time Russia has vetoed a vote on a Syria resolution.
Foreign Secretary Boris Johnson said he was “dismayed” at Russia's decision to veto the resolution, saying it put the country on the "wrong side of the argument".
It comes after US Secretary of State Rex Tillerson warned that trust between Moscow and Washington had plunged to a “low level” amid rising tensions over the war in Syria.
Russian President Vladimir Putin meanwhile said trust had eroded between the two countries since Donald Trump became president, after the new US leader fired missiles at Syria to punish Moscow's ally for its suspected use of poison gas.
Mr Tillerson met Russian foreign minister Sergei Lavrov for talks on Wednesday, during which Mr Lavrov reportedly said Russia was willing to reinstate an air safety agreement put on hold last week aimed at preventing accidents between US and Russian jets in the skies above Syria.
Russia’s top diplomat said after the talks that the pair had agreed to continue discussions aimed at securing a peaceful solution to the Syrian civil war, but warned of attempts by groups to sabotage relations with the US.
Earlier on Wednesday, British scientists told the UN Security Council they had found sarin in samples taken from the site of an alleged chemical gas attack, while Turkey also claimed to have found evidence of sarin gas use after testing the bodies of the victims.
The majority of the international community has blamed the attack in Idlib province, which killed 87 people including many children, on Syria's President Bashar al-Assad.
The Syrian government has meanwhile denied involvement in the toxic attack, blaming rebel groups.