Meanwhile, U.S. Secretary of State Hillary Clinton said she looked forward to trying to find a way to work with Russia to end the violence in Syria and support U.N.-Arab League envoy Kofi Annan's six-point peace plan for the violence-torn country.
"Up until now, as you know, there has not been support for the kind of political transition that is necessary under the Annan plan," Clinton said during a news conference in Oslo, Norway, following a meeting on global health issues.
"So I repeat the appeal that I have made to Russia because their position of claiming not to take a position is certainly viewed in the [U.N.] Security Council, in Damascus, and elsewhere as a position supporting the continuity of the Assad regime," Clinton said. "And if Russia is prepared, as President (Vladimir) Putin's remarks seems to suggest, to work with the international community to come together to plan a political transition, we will certainly be ready to cooperate."
High Commissioner for Human Rights Navi Pillay said during a special session of the U.N. Human Rights Council in Geneva, Switzerland, that there was a need for "prompt, independent and impartial international investigations" into all serious human rights violations.
Friday's meeting focused on the deteriorating human rights situation in Syria and the recent slaughter of 108 civilians in the village of Houla, the United Nations said in a release.
Pillay urged the international community "make all efforts to end impunity, to ensure accountability for perpetrators and to provide adequate and effective remedies for the victims."
The meeting was the council's fourth special session on Syria since the crisis began in March 2011. The United Nations estimates that more than 9,000 people, mostly civilians, have been killed and tens of thousands of people displaced since the uprising against President Bashar Assad began.
"These acts may amount to crimes against humanity and other international crimes, and may be indicative of a pattern of widespread or systematic attacks against civilian populations that have been perpetrated with impunity," Pillay said.
Pillay also expressed regret that the Syrian government hasn't granted the International Commission of Inquiry on Syria access to the country and called on Syria to assume its responsibility to protect the country's civilian population.
"I reiterate that those who order, assist or fail to stop attacks on civilians are individually criminally liable for their actions. Other states have a duty to do all they can to prevent and prosecute perpetrators of international crimes," she said, urging the U.N. Security Council to consider referring the case of Syria to the International Criminal Court in The Hague, Netherlands.
Besides the cease-fire, the plan calls for an end to violence, access for humanitarian agencies to provide relief to those in need, the release of detainees, the start of inclusive political dialogue that takes into account the aspirations of the Syrian people, and unrestricted access to the country for the international media.
In Oslo, Clinton said Western nations have known "that there has been a very consistent arms trade, even during this last year of violence in Syria, coming from Russia to Syria," which has strengthened the Assad regime.
"What those arms are being used for, we cannot speak with any accuracy but the fact that Russia has continued to sustain this trade in the face of efforts by the international community to impose sanctions and to prevent further arms flowing to the Assad regime and in particular the Syrian military has raised serious concerns on our part," Clinton said.
Noting she was meeting with various world and humanitarian leaders to discuss the situation in Syria, Clinton said, "[If] Russia is prepared to help us implement all of the six parts of Kofi Annan's plan, we are prepared to work with them to do so."
Meanwhile, the Assad regime faced a Friday deadline imposed by the Free Syrian Army, which warned the regime to abide by Assad's six-point peace plan. If not, the armed opposition group, largely composed of defected Syrian army personnel, would "no longer be tied by any commitment to the Annan plan ... and our duty will be ... to defend civilians."