ALEPPO, Syria - President Bashar al-Assad's forces used artillery, planes and a helicopter gunship to pound rebel positions in Syria's biggest city on Saturday, witnesses said, in a battle that could determine the outcome of the 17-month uprising.
After U.N. Security Council paralysis on Syria forced peace envoy Kofi Annan to resign this week, and with his ceasefire plan a distant memory, rebels were battered by the onslaught they had expected in Aleppo and in the capital Damascus.
"There is one helicopter and we're hearing two explosions every minute," said a Reuters witness in Aleppo, Syria's commercial hub.
Syrian forces struck at Aleppo's Salaheddine district, a gateway into the city of 2.5 million people that has become the frontline of an increasingly sectarian conflict that has killed some 18,000 people and could spill into neighbouring countries.
A local rebel commander said his fighters were preparing for a "strong offensive" by government forces on the city.
In Damascus, jets bombarded the capital as troops continued an offensive they began on Friday to storm the last rebel bastion there, a resident said.
Both cities - vital prizes in the battle for Syria - had been relatively free from violence during the 17-month uprising but fighting flared in Damascus after a July 18 bombing which killed four of Assad's inner circle and also erupted in Aleppo.
"We saw two fighter bombers that are each capable of carrying one bomb fly over the area of Salaheddine and then we heard two explosions," said a witness.
Early on Saturday, a rebel commander in Aleppo said he expected a Syrian army attack on rebels "within days", echoing the head of the U.N. peacekeeping department, who said there had been a "considerable build-up of military means".
"We know they are planning to attack the city using tanks and aircraft, shooting at us for three to four days and they plan to take the city," Colonel Abdel-Jabbar al-Oqaidi said.
Bullets zipped past residential buildings, as rebels took cover behind concrete blocks and sandbag walls and fired in the direction of Assad's forces. Two fighter jets opened fire with cannon and smoke billowed from the district.
One fighter fell to the ground after a bullet hit his chest. Fellow rebels dragged him into a car, leaving a trail of blood on the ground, to take him to a field hospital.
TV offensive repelled
Rebels tried to extend their area of control in Aleppo from Salaheddine to the area around the television and radio station, but were pushed back by Assad's troops, an activist said.
"The Syrian army sent snipers and surrounded the TV station and as soon as morning came, the army started shooting. One of our fighters was martyred and four were wounded," said a 19-year-old fighter, who gave his name as Mu'awiya al-Halabi.
Syrian television said a large number of "terrorists" were killed and wounded after they tried to storm the broadcaster.
After Annan's resignation, the U.N. General Assembly voted on Friday to condemn the Syrian government and criticise the U.N. Security Council's failure to agree tougher action, in a resolution that Western diplomats said highlighted the isolation of Assad supporters Russia and China.
Russia called the vote a "facade of humanitarian rhetoric" behind which Assad's foreign enemies were arming the rebels and worsening the violence that has elements of a proxy war between Sunni and Shi'ite Islam which could spill beyond Syrian borders.
Assad is a member of the Alawite faith, an offshoot of Shi'ite Islam that has dominated Syrian politics through more than 40 years of his family's rule in a country that has a Sunni Muslim majority.
The mostly Sunni Muslim Gulf Arab states and Turkey have called for Assad to go. Assad still has the backing of Shi'ite Iran and Lebanon's armed Shi'ite Hezbollah movement.
In Damascus, a resident in the Adawi neighbourhood just north of the central Old City reported that jets had pounded an area of the capital on Saturday. "The bombardment has been continuous since 7 a.m. (0400 GMT) in Tadamun district. It hasn't stopped for a moment," said the resident.
Syrian television said on Saturday an armed terrorist group had committed a massacre in the Damascus suburb of Yalda. The television station said 20 people had been killed. It was not immediately possible to verify the incident as Syria restricts foreign media access.
A bus-load of 48 Iranian pilgrims were abducted by gunmen in Syria on Saturday, Iranian and Syrian media reported, the latest in a string of kidnappings of visitors from the Islamic Republic.