Iran and China on Monday condemned killings in the Syrian town of Houla, blaming them on "terrorist actions" rather than its Damascus ally and calling for the perpetrators to be punished.
Iran "condemns the terrorist actions in the Houla area in Homs in Syria. The killing of a number of innocent people in the area has distressed the Islamic nations," the foreign ministry said in a statement relayed by official media.
It denounced the "suspect act" and urged authorities "to identify and punish those responsible."
Iran's statement followed strong condemnation on Sunday by the UN Security Council of a massacre, confirmed by UN observers in Syria, of at least 108 people, nearly half of them children, in Houla.
The Security Council text implicated Al-Assad's regime, saying the killings "involved a series of government artillery and tank shellings on a residential neighborhood," and called "such outrageous use of force" against civilians a violation of international law.
Iran's arch-foe Israel charged that Iran and its Lebanese militia ally Hezbollah were "an inseparable part of the Syrian atrocities" and called for international action against them.
The statement by Iran's foreign ministry implicitly rejected that accusation and appeared to place the blame for the Houla massacre on Syrian rebels, who Damascus has characterised as "terrorists".
Syria is Iran's chief ally in the Middle East, and Iran has been providing political and material support to Assad's goverment as it fights the rebels. Tehran, however, has denied US allegations that it is providing Assad's forces with weapons and military advisers.
The United Nations says more than 10,000 people have died in the Syrian conflict since it started 15 months ago. Syrian activists put the toll at more than 13,000.
The Chinese foreign ministry said it was "deeply shocked" by the killings and urged the swift implementation of UN-Arab envoy Kofi Annan's peace plan, a day after the UN condemnation statement.
But it stopped short of pointing the finger directly at the Syrian government, after Russia questioned whether Damascus was behind the violence.
"China is deeply shocked and strongly condemns the incident," said foreign ministry spokesman Liu Weimin.
"China... calls for an immediate investigation into this issue and to find the perpetrators. This incident again shows that Syria should waste no time to implement the ceasefire and end the violence," he added.
Beijing and Moscow – both long-standing allies of Damascus – drew international criticism earlier this year for vetoing two UN Security Council resolutions against Al-Assad's regime.
They have since backed Annan's efforts to bring peace to Syria. But the peace envoy's six-point blueprint, which was supposed to begin with a ceasefire from April 12, has been broken daily.
"We hope Annan will continue to play an active role and relevant parties will continue to provide support toward Annan's six-point proposal," Liu said.
"We urge relevant parties in Syria to immediately and comprehensively uphold relevant Security Council resolutions and Annan's six-point proposal, stop all violence, properly protect innocent civilians, ease tensions there and push forward the political resolution of the Syrian issue."
Syrian authorities have denied their forces carried out the Houla killings, which have sparked an international outcry, with a spokesman blaming "terrorists" and saying the government had opened an investigation.
More than 13,000 people have been killed in Syria since an anti-regime revolt broke out in March 2011, according to the Syrian Observatory for Human Rights, a watchdog group.