66 Dead across Syria as Troops Assail Rebels in Aleppo

Troops backed by helicopters pushed an offensive against rebels in Syria's commercial capital Aleppo into a second straight day on Sunday, sparking fierce fighting and sending civilians fleeing.

The opposition Syrian National Council (SNC) accused the government of preparing to carry out "massacres" in the northern city and pleaded for heavy weapons to enable rebels to meet the onslaught.

It also urged the U.N. to hold an emergency session to discuss ways to protect civilians caught up in the conflict.

Syrian Foreign Minister Walid Muallem, on a surprise visit to key ally Iran, said the rebels "will definitely be defeated" in Aleppo, even as a Free Syrian Army (FSA) commander boasted the city would become a "graveyard" for the army's tanks.

The Syrian Observatory for Human Rights said Sunday's fighting was focused around the southwestern neighborhood of Salaheddin, where rebels repulsed a ground assault on Saturday.

"There are clashes on the edges of... Salaheddin" which regime forces were pounding with helicopter gunships, the Observatory's Rami Abdel Rahman told Agence France Presse.

Abdel Rahman described the situation in Aleppo as "a full-scale street war," with fighting also in the neighborhoods of Arkoub, Bab al-Hadid, Fardoss, Jisr al-Hajj, Sukari, Zahraa, Zebdiyeh, at the al-Hindrat Palestinian refugee camp, and Bustan al-Qasr district which was being pounded by helicopter gunships.

The Britain-based Observatory said that "the sound of heavy machinegun fire and explosions" could be heard in Salaheddin late on Sunday but gave no further details.

Rebels broke into a juvenile detention center "in order to set the prisoners free," he said, adding displaced families were having difficulty finding refuge "because nowhere is safe anymore."

After massing for two days, troops backed by tanks and helicopters on Saturday launched a ground assault on Salaheddin, where rebels concentrated their forces when they seized much of Aleppo on July 20.

Both sides claimed to have made advances, but an AFP correspondent reported rebels had largely repulsed the army when it launched its first onslaught.

Civilians in the city of some 2.5 million crowded into basements seeking refuge from the intense bombardment by artillery and helicopters, the correspondent said.

Colonel Abdel Jabbar al-Oqaidi, FSA commander for Aleppo, said the rebels had inflicted heavy losses on the army in Salaheddin but that there had been many civilian deaths.

"We have destroyed eight tanks and some armored vehicles and killed more than 100 soldiers," he said.

"Aleppo will be the graveyard of the tanks of the Syrian army," Oqaidi told AFP in an interview conducted at an isolated farmhouse surrounded by olive groves near the city.

"We ask the West for a no-fly zone" in order to prevent aerial raids by Assad's forces, he said.

The colonel said his men were positioned across Aleppo and would not withdraw as they had when they came under intense fire from regime troops in Damascus earlier this month.

"There is no strategic withdrawal of the Free Syrian Army. We await the attack," he said, while refusing to reveal how many rebels are fighting in Aleppo.

"We expect (the army) to commit a very great slaughter, and we urge the international community to intervene to prevent these crimes," the colonel said.

The Observatory reported that by late afternoon seven people were killed in Aleppo, contributing to a nationwide death toll of 66: 25 civilians, 19 troops and 22 rebels.

In Tehran, Muallem vowed regime forces would crush the rebels in Aleppo.

"We believe that all the anti-Syrian forces have gathered in Aleppo to fight the government... and they will definitely be defeated," he told a joint news conference with Tehran's Foreign Minister Ali Akbar Salehi.

Muallem also met President Mahmoud Ahmadinejad, who told him that he hoped Syria's government would restore "stability" in the country quickly, Iran's ISNA news agency said.

Syria's Muslim Brotherhood denounced Iran and Russia, saying the powerful allies of the embattled Assad regime were "drowning in the blood of the Syrian people."

As the rebels faced the superior firepower of Assad's regime, SNC chief Abdel Basset Sayda called on foreign governments to provide them with heavy weapons.

"We want weapons that would stop tanks and jet fighters," Sayda said after talks in Abu Dhabi.

The SNC also called on the Security Council to hold an emergency session on the situation in Aleppo, Damascus and Homs and urged it to "take action to provide civilians with the needed protection from brutal bombing campaigns."

Peace envoy Kofi Annan urged both sides to hold back, saying only a political solution could end a conflict that rights activists say has killed more than 20,000 people since the uprising erupted in March 2011.

"The escalation of the military build-up in Aleppo and the surrounding area is further evidence of the need for the international community to come together to persuade the parties that only a political transition, leading to a political settlement, will resolve this crisis," he said.