Russia is fast becoming a pariah nation in the eyes of the world

Damaged trucks and supplies in the aftermath of an attack on a humanitarian aid convoy in Aleppo Province

London (AFP) - 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.

"If they continue like this they will forfeit any sympathy and any admiration in the world at all, and I think they do care about that.

"In the end, if (President Vladimir) Putin's strategy is the greatness and glory of Russia then he risks seeing that turned to ashes as people view his actions with contempt."

A short-lived truce brokered by Moscow and Washington last month fell apart as both sides blamed each other for its failure.

Moscow has since been accused of indiscriminately bombing rebel-held eastern Aleppo in support of an assault by Syrian government troops aiming capture all of the country's second city. An estimated 275,000 people live in the rebel-held districts of Aleppo.

France on Friday discussed a UN draft resolution on imposing a ceasefire in the battleground city with Russia, the United States and the two other permanent Security Council members, diplomats said.

Russia escalated its anti-American invective Thursday in the deadlocked diplomacy over the Syrian war, dismissing a threat by Secretary of State John Kerry to halt talks and accusing his spokesman of abetting global terrorism — including against Russian military personnel in Syria.

The Russian response came as United Nations officials warned that 600 wounded civilians in the rebel-held districts of the divided northern city of Aleppo must be evacuated and that food is nearly exhausted for the 275,000 residents trapped there.

The residents have been pummeled for the past week by Syrian and Russian airstrikes, including by powerful bombs that can pulverize underground shelters. The top emergency relief official for the United Nations, Stephen O’Brien, told the Security Council on Thursday that Aleppo faced a “humanitarian catastrophe unlike any we have witnessed in Syria.”

The Russians, the main military allies of President Bashar al-Assad, offered 48-hour pauses in Aleppo to permit humanitarian access, an idea that Western diplomats and United Nations officials have rejected as impractical and meaningless. Mr. Kerry has demanded a return to the cessation of hostilities agreement he negotiated with Foreign Minister Sergey V. Lavrov on Sept. 9, which collapsed a week later.

In some of his strongest criticism of Russia over the Syria conflict, Mr. Kerry said Wednesday that unless the Syrians and Russians quit their barrage of Aleppo and restored the Sept. 9 agreement, the United States would suspend talks and scrap a plan to collaborate with Russia on targeting jihadist fighters in Syria that both powers regard as terrorist threats.