DAMASCUS/BEIRUT: Syrian government jets bombarded the Damascus Ring Road Thursday in a bid to halt a rebel advance on the capital, insurgent commanders and opposition activists said, as Islamic states urged Syria’s regime and its foes to hold “serious” talks to end the bloodshed.

Troops overran the rebel town of Karnaz on the strategic Damascus-Aleppo highway after a 16-day onslaught, said Rami Abdel-Rahman of the opposition activist group the Syrian Observatory for Human Rights.

The combatants were also locked in a second day of fierce clashes around Damascus after opposition forces launched a surge in to the center of the city Wednesday.

Government warplanes fired rockets at southern parts of the Ring Road route where rebels have spent the past 36 hours overrunning army positions and road blocks encircling the heart of the city, the site of key state security and intelligence installations.

“The regime really wants its positions on the ring road back. It is a major defense line for the capital,” Aby Ghazi, a rebel commander based in the eastern suburb of Irbreen told Reuters.

Aby Ghazi said the rebels had reached the edges of the capital’s main Abbasid Square where the Syrian military had turned a football stadium into barracks.

Syrian Authorities have banned most international media from the country, making it difficult to verify events on the ground.

Units of Assad’s elite Republican Guard based on the Qassioun Mountain overlooking the capital fired artillery rounds and rockets at Jobar, an eastern neighborhood bordering the square, and at the Ring Road, rebel and activist sources said.

Damascus residents, long accustomed to the sounds of war, said Thursday’s shelling was some of the heaviest they had heard.

“They’ve gone insane. All of them. They’re insane,” one central Damascus resident said by telephone.

With neither side gaining a clear military advantage in the civil war, world powers fear the conflict could envelop Syria’s neighbors, further destabilizing the region.

Concluding the second day of talks, leaders of Muslim nations called Thursday for a “serious dialogue” between Syria’s government and an opposition coalition on a political transition to end nearly two years of civil war, but pinned most of the blame for the bloodshed on the state.

The two-day summit of the 57-member Organization of Islamic Cooperation backed an initiative by Egypt, Turkey, Iran and Saudi Arabia to broker negotiations to stop the fighting.

“We all agreed on the necessity to intensify work to put an end to the tragedies which the sisterly Syrian people are living through,” Egyptian President Mohammad Mursi told the closing ceremony.

The final communique, issued hours after the summit ended because of last-minute wrangling over the wording, said Assad’s government was most to blame.

“We stress that the primary responsibility is on the Syrian government for the continuation of violence and destruction of property, and we express our deep concern at the deterioration of conditions and the spread of killings that led to the deaths of thousands of innocent civilians and the Syrian authorities’ commission of massacres in cities and villages,” it said.

Syrian ally Iran had “reservations about a passage or two” in the statement on Syria, outgoing OIC chief Ekmeleddin Ihsanoglu said. Iraq and Lebanon also expressed reservations about the text, according to a source close to delegates.

The statement made no mention of Assad but called for talks between the opposition Syrian National Coalition and “representatives of the Syrian government who are committed to the political transformation of Syria and those who have not been involved directly in any form of oppression”.

It also urged all other opposition groups to join the Syrian National Coaltion, headed by Ahmad Moaz Khatib..

Khatib made a surprise offer last weekend of talks with Assad’s ceremonial deputy, Farouq Sharaa, on a transition that would guarantee Assad safe passage into exile.

The presidents of Egypt, Turkey and Iran met on the margins of the summit to discuss ways to support the initiative. Mursi said more details of their plan would be announced within days.

As yet there has been no official response from Damascus to offer by Khatib, who has given the Syrian government until Sunday to release all women detainees, otherwise he would regard his offer for dialogue as having been rejected.

State media said Thursday the army had pushed back rebels from Jobar and other eastern districts.

It added that six people, including a woman and three children, were killed by rebel mortar fire on a bus station in the north-eastern district of Qaboun Thursday, with several other people seriously wounded.

Video footage showed rebels inspecting several bodies identified as government soldiers and pro-Assad militiamen killed in fighting on Thalatheen street, a main Damascus thoroughfare straddling the southern rebel-held district of Hajar al-Aswad.

The Observatory said at least 92 people who died in nationwide violence, according to a preliminary toll, mostly from heavy army bombardment on the contested neighborhoods of Jobar and Zamalka, which are near compounds housing Alawite forces.

A retired military officer in Damascus said that the shelling of rebel-held areas was hitting civilians and fighters indiscriminately.

Regime troops “stand hundreds of meters away and fire shells. And the shells fall on anyone. Women and families and anybody. Where is the courage in that,” he added.