The UN chief and his Syria envoy said Saturday they are prepared to broker peace talks between the regime and opposition, as Damascus ally Iran said Bashar al-Assad would stand again for president in 2014.
A joint statement by Ban Ki-moon and Lakhdar Brahimi said the UN would "be prepared to facilitate a dialogue between a strong and representative delegation from the opposition and a credible and empowered delegation from the Syrian government."
They met after both sides in Syria had indicated a "willingness to engage in dialogue," the UN said.
"Both expressed deep frustration at the failure of the international community to act with unity to end the conflict which has left over 70,000 dead and resulted in a massive human displacement within and outside of the Syrian borders," the statement said.
They also warned that both the regime and opposition fighters "have become increasingly reckless with human life" and said perpetrators of war crimes and crimes against humanity must be brought to justice.
In Tehran on Saturday, Iranian Foreign Minister Ali Akbar Salehi said Assad will take part in next year's presidential election and that it is up to the Syrian people to choose their own leader.
He spoke during a visit by Syrian Foreign Minister Walid Muallem for talks on the nearly two-year conflict.
At a joint news conference, Salehi said "in the next election, President Assad, like others, will take part, and the Syrian people will elect whomever they want."
The "official position of Iran is that... Assad will remain legitimate president until the next... election" in 2014.
Assad, who took over as president in 2000 following the death of his father Hafez, has repeatedly rejected opposition, Western and Arab calls to step down.
A new constitution adopted in February 2012 stipulates that he can run for the presidency twice from 2014, which means he could stay at the helm until 2028 if re-elected.
Salehi also backed a call by Damascus for talks with the armed opposition, calling the initiative a "positive step," but reiterated that Assad's regime has "no choice" but to keep fighting rebels.
"We believe that the crisis has no military solution and only a Syrian political one," he said.
Muallem condemned the announcement by US Secretary of State John Kerry on Thursday that Washington would provide $60 million in "non-lethal" assistance to support Syria's political opposition.
"When the US (says it has) allocated $60 million to the opposition and this opposition is killing people, I don't understand this initiative... Are there any weapons that do not kill people? Who are you kidding?" Muallem asked.
He repeated calls for pressure to be exerted on Turkey and Qatar, among the main supporters of the rebels alongside Western countries.
Damascus has repeatedly blamed foreign-backed "terrorists" for the violence, using the term to refer both to rebels and peaceful opponents ever since the outbreak of a popular revolt against Assad in March 2011.
On the ground, the army said on Saturday it seized control of a key road linking the central province of Hama to Aleppo international airport, the scene of fierce battles since mid-February.
The Syrian Observatory for Human Rights said this was significant because it will allow new troop deployments and supplies to reach the area surrounding the airport and nearby Nayrab military airbase.
Fierce clashes also raged in the northern city of Raqa between rebels and troops, killing at least 26 fighters -- 16 rebels and 10 soldiers, Observatory chief Rami Abdel Rahman said.
The Britain-based Observatory and activists said military helicopters strafed rebels in some parts of Raqa, which Abdel Rahman said was home to about 800,000 people displaced by violence elsewhere in Syria.
At least 133 people were killed nationwide on Saturday, the Observatory said.
They included two Palestinians hanged by rebels from trees at Yarmuk refugee camp in Damascus on suspicion of aiding the regime, the Observatory said. The two were suspected of pinpointing rebel targets for regime forces.
The Israeli military said mortar rounds believed to have been fired from Syria hit the southern Israeli-occupied Golan Heights on Saturday without causing damage or casualties.
The Observatory said there had been clashes in the Quneitra area, with two rebels and an unknown number of soldiers killed.