Ex-diplomats and Nobel laureates urged the UN Security Council on Monday to stop the violence in Syria, warning "paralysing" splits in the international community had given the regime a licence to kill.
In a letter published in the Financial Times and to be published in Le Figaro in France on Tuesday, they called on Russia in particular to help stop President Bashar al-Assad's bloody crackdown on protests.
"Splits among the international community have provided the Assad government with a licence to kill. This licence must be withdrawn," the letter said.
It said the crackdown was "among the worst cases of deliberate violence against a civilian population that we have seen in recent years".
"While we understand that there is no easy way out of this crisis, the moral obligation to bridge the current impasse lies with the members of the Security Council," the letter continued.
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"Let there be no mistake, the credibility and international standing of any nation standing idle in the face of the avoidable tragedy unfolding in Syria will be severely damaged."
China and Russia have drawn heavy criticism for using their veto powers as permanent members of the United Nations Security Council to block resolutions condemning the crackdown, because they singled out Assad for blame.
The FT letter said Russia should "join collective efforts to bring a swift end to the conflict", and called on unanimous support for UN-Arab League peace envoy Kofi Annan to help him "overcome the present paralyising divide".
It called for a UN Security Council resolution urging the Syrian regime to end all unlawful attacks against the population immediately, release all political prisoners and facilitate the delivery of independent and impartial emergency aid.
Signatories include Paddy Ashdown, former High Representative for Bosnia and Herzegovina; former Brazilian president Fernando Henrique Cardoso; former UN diplomat Jan Egeland; former South African president F.W. de Klerk; former German president Richard von Weizsacker; former secretary in India's foreign ministry K.C. Singh and former Jordanian foreign minister Marwan Muasher.
Nobel peace laureates Shirin Ebadi of Iran and Leymah Gbowee of Liberia also signed the letter, as did Clovis Maksoud, former ambassador of the League of Arab States, and Canadian former foreign minister Lloyd Axworthy.