This is the eighth time that Russia has used its UN veto to protect the Syrian government since the civil war began
Russia has vetoed a UN Security Council resolution demanding a swift investigation into a chemical weapons attack in Syria.
Wednesday’s vote saw ten countries in favour of the resolution drafted by Britain, France and the US.
Russia and Bolivia were against - while China, Kazakhstan and Ethiopia abstained.
In addition to an investigation, the resolution would have condemned the use of chemical weapons in the rebel-held town of Khan Sheikhoun on 4th April.
The Syrian regime and its backers, including Russia, have denied President Bashar al Assad was responsible.
They have said the attack in Idlib province, which killed more than 80 people, was either a rebel provocation or the result of Syrian planes hitting a rebel weapons factory.
This is the eighth time that Russia has used its veto power at the UN Security Council to block action directed at Damascus since the bloody civil war began in 2011.
Nikki Haley, the US ambassador to the United Nations, has urged Moscow to stop protecting the Assad regime, and said it stands alone as "the rest of the world - including the Arab world - overwhelmingly comes together to condemn this murderous regime".
"If the regime is innocent, as Russia claims, the information requested in this resolution would have vindicated them," she told the council.
Russia's deputy ambassador to the UN, Vladimir Safronkov dismissed a British report claiming the nerve agent, sarin had been detected on samples taken from the Syria chemical attack.
Mr Safronkov told the council he was “amazed at this conclusion.”
"No one has yet visited the site. How do you know that?" he asked.
Mr Safronkov also said America's cruise missile strike on a Syrian airbase "was carried out in violation of international norms."
Russia - along with Britain, China, France and the US - are permanent members with veto powers, while the other 10 members are elected for two-year terms on a rotating basis.