BEIRUT (AP) -- Fierce fighting broke out around the northern Syrian city of Aleppo Friday as rebels announced a large-scale offensive to break the government's nearly two-month siege of opposition-held areas.
A reporter inside the city on the Lebanon-based Al-Mayadeen TV channel reported attacks on "all sides" of the city, "from the furthest points north to furthest south."
Sounds of heavy gunfire, mortar fire, and explosions were heard in the background of his broadcast. Dark smoke was seen rising above the city on the overcast morning. Presumed government or Russian jets were also heard flying overhead.
Rebel factions in and around Aleppo have been preparing to launch a counteroffensive to try and break the government's suffocating siege off Aleppo's eastern-held neighborhoods for several weeks.
The area has been subjected to a ferocious campaign of aerial attacks by Russian and Syrian government warplanes, and hundreds of people have been killed in recent weeks according to opposition activists and trapped residents.
The Syrian army said in a statement that troops repelled rebel attacks on all fronts in Aleppo and inflicted human losses among the attackers.
The army said the rebel attack concentrated on the Assad suburb west of Aleppo amid intense shelling with artillery and Russian-made Grad rockets.
"The Syrian army and its allies are in control on the ground and armed groups were not able to change the map," the army statement said. "Fighting is still ongoing but the intensity dropped."
This is the second attempt by rebels to break the government's siege. They opened a corridor to the east for the month of August after pro-government forces first applied a blockade in July, but government forces were able to reinstate the siege in early September.
Rebels launched the offensive Friday as the Russian, Syrian, and Iranian foreign ministers met in Moscow. Iran and Russia are Assad's main backers and have committed air power, ground forces, and military advisers to the war.
Aleppo is the focal point of the six-year war. President Bashar Assad has said he is determined to retake the country's largest city and former commercial capital. The government has maintained a siege on the rebel-held eastern quarters since September. The U.N. estimates 275,000 people are trapped inside with dwindling supplies of food and medicine.
Friday's attack began with rebels detonating three vehicle-borne explosives against government positions to the city's southwest and attacking with hundreds of rockets, the Britain-based Syrian Observatory for Human Rights said. It said at least one of the vehicles was driven by a suicide bomber for the al-Qaida-linked Fatah al-Sham Front, which also announced the offensive.
Fatah-al-Sham claimed credit for two car bombs, saying in a statement that a "martyrdom-seeking fighter" drove a tank laden with explosives and parked it, before it was detonated and the fighter "returned to his brothers."
In a second statement it said a suicide car bomb attack was carried out west of Aleppo.
The Islamic Front rebel coalition also announced on Twitter that the ultraconservative Ahrar al-Sham group targeted a military airport to the east of the city with Grad rockets and destroyed a government position to the west of the city.
Ammar Sakkar, the military spokesman for the powerful Fastaqim faction inside the city, said "all the revolutionary factions, without exception, are participating in the battle."
He said hundreds of advance fighters were participating in the attack, adding that the total number of participants was "much higher."
In Moscow, Syrian Foreign Minister Walid al-Moallem told his Russian counterpart that the government in Damascus is "determined to liberate all our land from terrorists."
"Our goals are common, therefore coordination between us continues on almost daily basis and we are thankful" for Russia, al-Moallem said.