Syria conflict: Brahimi in first mission
The new UN-Arab League envoy to Syria, Lakhdar Brahimi, has begun his first mission with a visit to Cairo, where he acknowledged the challenges.
Mr Brahimi, who replaces Kofi Annan, said it was a "very difficult mission".
He is due to visit the Syrian capital, Damascus, in the coming days.
On the ground, violence continued with at least 20 Syrian soldiers killed by rebels in Syria's largest city, Aleppo, according to a UK-based opposition activist group.
The killings took place over the weekend, according to the Syrian Observatory for Human Rights.
Its website showed images of the bodies of men, many wearing military fatigues, lying by the side of the pavement, apparently shot. They had been blindfolded and had their hands ties behind their backs.
Observatory director Rami Abdel Rahman told Agence France Presse that the soldiers had been captured at a military compound during a rebel attack in the city's eastern district of Hanano.
Reports from Syria are almost impossible to verify because of severe restrictions on foreign journalists in the country.
The killing of the soldiers came just ahead of a car bomb attack in Aleppo on Sunday which killed dozens, including many troops.
State TV reported the targets included two hospitals and a school. The Free Syrian Army said it had carried out the attack because the facilities were being used by government troops.
Mr Brahimi is holding meetings in Cairo ahead of a visit to Syria where he said he would meet officials and civil society representatives in the capital and beyond.
"I realise it's a very difficult mission, but I think it is not my right to refuse to give whatever assistance I can to the Syrian people," he told reporters after talks with Arab League Secretary General Nabil al-Arabi.
When he took over the post, Mr Brahimi said bringing peace to Syria would be "nearly impossible". He has described the bloodshed there as "staggering" and the destruction as "catastrophic".
Iran has said that it is joining officials from Egypt, Saudi Arabia and Turkey for a four-way meeting in Cairo of a "contact group" proposed by Egyptian President Mohammed Mursi, AFP reports.
The group aims to look at ways of stopping the bloodshed in Syria where, according to the UN, more than 18,000 people have been killed since the conflict began in March 2011. Activists put the death toll at 23,000.
The UN High Commissioner for Human Rights, Navi Pillay, said on Monday that both sides in the conflict were to blame for human rights abuses.
She said she was concerned by the use of heavy weapons and the shelling of highly populated civilian areas by the government, as well as violations carried out by the anti-government forces, including murder and extrajudicial execution and torture.
Mr Brahimi's visit comes amid an impasse in efforts to find a diplomatic solution to the fighting.
On Sunday, US Secretary of State Hillary Clinton dismissed a Russian proposal for a new UN Security Council resolution on Syria as pointless as it had "no teeth".
Russia says it wants Security Council approval for a peace plan agreed in June in Geneva that called for a ceasefire and political transition.
But Mrs Clinton said a resolution without consequences would be ignored by Syrian President Bashar al-Assad.
She said that if differences with Moscow persisted, "then we will work with like-minded states to support a Syrian opposition to hasten the day when Assad falls".