Russia risks becoming 'pariah nation': Britain's Johnson

British Foreign Secretary Boris Johnson said Russia was in danger of becoming a pariah nation, as he hit out at alleged "double tap" bombing raids in Syria, hitting aid workers.

"They drop one bomb and then they wait for the aid workers to come out, civilian people pulling the injured from the rubble, and then five minutes later they drop another bomb," he told The Sun newspaper.

Johnson said the British government had evidence that Russian jets had carried out such attacks, which were "unquestionably a war crime".

"We have evidence. We have good ground to believe that the Russians themselves have been doing that.

"We are trying to document that fully because that is in my view unquestionably a war crime."

He said Britain and the United States were looking at a "range of options" designed to ramp up the pressure on Moscow.

"The single most potent weapon we have is shame," he said.

"The world's attitude towards Russia has been hardening and I think people now believe that Russia is in danger of becoming a pariah nation."