Syrian National Coalition leader Moaz Alkhatib said on Sunday he was willing to hold talks with President Bashar al-Assad's representatives in rebel-held areas of northern Syria to try to end a conflict that has killed about 60,000 people.
The aim of the talks would be to find a way for Assad to leave power with the "minimum of bloodshed and destruction", Alkhatib said in a statement published on his Facebook page.
Sources in the coalition, an umbrella group of opposition political forces, said that Alkhatib, a moderate cleric from Damascus, met international Syria envoy Lakhdar Brahimi in Cairo on Sunday.
Brahimi played a main role in organizing meetings between Alkhatib and the foreign ministers of Russia and Iran, Assad's main supporters, in Munich last week.
The sources said that in their talks on Sunday the two men addressed the question of whether the coalition would formally endorse Alkhatib's peace initiative.
The Muslim Brotherhood, which controls a large bloc within the Islamist-dominated coalition, is against the initiative.
But the Brotherhood, the only organized political force in the opposition, is unlikely to challenge Alkhatib's authority directly, with his initiative gaining popularity in Syria, the sources said.
The Syrian authorities have not responded directly to Alkhatib's initiative -- formulated in broad terms last month. But Information Minister Amran al-Zubi on Friday repeated the government's line that the opposition was welcome to come to Damascus to discuss Syria's future in line with Assad's proposals for a national dialogue.
Alkhatib has headed the Syrian National Coalition since it was founded last December in Qatar with Western and Gulf backing. He has quietly built a student following and links with civic and religious figures across Syria.
His latest offer of talks coincided with opposition reports of fighting moving closer to central Damascus, after a rebel push into the east of the capital last week.
The Local Coordination Committees, a network of grassroots activists, said clashes broke out on Sunday in the al-Afif neighborhood of Damascus, which is adjacent to a presidential complex.
The organization said 77 people were killed in Syria on Sunday, including 16 people who it said had been executed by Assad's forces in the eastern city of Deir al-Zor. Such reports are impossible to verify as Syria severely restricts access for independent media.
The war is pitting Assad's minority Alawite sect, an offshoot of Shi'ite Islam that has dominated Syria since 1960s, against the Sunni majority that has led the protest movement.
When Alkhatib made his offer of talks last month, he made this conditional on the authorities starting to release tens of thousands of political prisoners jailed since the eruption of the 22-month uprising.
The United Nations said on Friday that it saw a glimmer of hope in Alkhatib's offer.
U.N. Under-Secretary-General for Political Affairs Jeffrey Feltman said the offer was "the most promising thing we've heard on Syria recently".
On Sunday, Alkhatib spelt out ideas on a venue for talks.
He said: "If the regime is so concerned about sovereignty and does not want to venture out of Syrian territories, then there is a suitable solution, which is the liberated land in northern Syria."
He added: "There is an important question. Will the regime agree to leave with the minimum of blood and destruction?"
Syria's uprising, which started as peaceful protests against four decades of autocratic rule by Assad and his late father, has turned into a violent sectarian conflict.
Freedom for political prisoners is an important issue for the opposition. Alkhatib said even centrist opposition figures who were willing to talk with Assad, such as Abelaziz al-Khayyer, a veteran Alawite human rights campaigner, have been jailed.
"The regime deals with the demands to release the political prisoners, especially the women, in a totally inhumane way," Alkhatib said. "Despite two years of savage killing, the regime is still trying to buy time."
The scion of a religious family who have historically been custodians in the Umayyad mosque in Old Damascus, Alkhatib was a proponent of a negotiated solution while he was in Syria. But he was jailed several times during the revolt in secret police dungeons and was forced to flee the country.
Alkhatib said the regime missed a "rare opportunity' by not agreeing to release women prisoners by a deadline he had set for Sunday, but that he was compelled morally to continue to try to negotiate a peaceful exit for Assad.
(Additional reporting by Yasmine Saleh in Cairo; Editing by Stephen Powell)