Syrian regime forces and rebel factions sent hundreds of reinforcements to Aleppo on Monday as opposition fighters announced an all-out offensive to take the country's second city.

The battle for Syria's former economic powerhouse is intensifying after an opposition advance at the weekend broke through a three-week government siege of the city's rebel-held east, dealing a major setback to regime troops.
Rebel forces on Sunday announced a bid to capture all of Aleppo city, which if successful would mark the biggest opposition victory yet in Syria's five-year civil war.
But forces loyal to President Bashar al-Assad are putting up a fierce fight and have begun pouring reinforcements into the city.
The Syrian Observatory for Human Rights, a monitoring group, said some 2,000 pro-regime fighters from Syria, Iraq, Iran and Lebanese Shia movement Hezbollah had arrived in Aleppo since late Sunday.
"Both sides are amassing their fighters in preparation for the great battle of Aleppo," said Rami Abdel Rahman, the head of the Britain-based Observatory.
The Monday edition of Al-Watan, a Syrian daily close to the government, reported that the army had received "the necessary military reinforcements to launch the battle to retake the areas from which it withdrew."
Citing a source on the ground, the paper said military warplanes "are carrying out a barrage of air strikes targeting the armed groups."

'New phase to liberate Aleppo'

Aleppo has been roughly divided between government forces in the west and rebel groups in the east since fighting first broke out there in mid-2012.
After years of stalemate, fighting for the city entered a new phase last month when government forces took control of the last supply road into rebel-held areas, leaving some 250,000 people in eastern districts surrounded.
In a desperate bid to break the siege, a coalition of rebels, Islamists and jihadists overran a series of buildings in a military academy on the southwestern edges of Aleppo on Saturday.
They then pushed northeast to link up with rebel groups inside the city.
Emboldened by the victory, the fighters -- largely grouped under the banner of the Army of Conquest -- then set their sights on recapturing all of Aleppo city.
In a statement on Sunday the Army of Conquest announced "the start of a new phase to liberate all of Aleppo," pledging to "double the number of fighters for this next battle."
Abdel Rahman told AFP on Monday that hundreds of opposition fighters had arrived in Aleppo from the surrounding province and neighbouring Idlib.
Most were from the Fateh al-Sham Front, the powerful jihadist group previously affiliated with Al-Qaeda that leads the Army of Conquest. The group changed its name from Al-Nusra Front last month after breaking with Al-Qaeda.
Fateh al-Sham boasted at the weekend that it had captured military vehicles and artillery from government positions.

Aid to regime areas

Residents of both sides of the city have been living in fear of competing sieges of their neighbourhoods in recent weeks.
The rebel advance at the weekend cut off a key regime access route on the city's southern edges, which had been used to bring in supplies for the estimated 1.2 million residents of western districts.
Overnight, regime forces brought in dozens of trucks carrying food and fuel into the western neighbourhoods via the northern Castello Road, according to the Observatory.
"This is the new route that the regime forces are securing as a temporary alternative to the route they previously depended on," Abdel Rahman said.
Syrian state television Al-Ikhbariyah confirmed that "fuel, food, and vegetables entered Aleppo city."
A military source in Damascus denied that the city's west had been besieged, saying "the situation is under control and the situation is not worrisome."
Seven trucks of fruits and vegetables entered the eastern rebel-held districts on Sunday and were quickly purchased by residents.
More than 280,000 people have been killed since Syria's conflict erupted in March 2011 with anti-government protests.
Half of the pre-war population has been displaced, including an estimated five million people seeking refuge in neighbouring countries.
International efforts to resolve the conflict have repeatedly failed though the United Nations is hoping that peace talks can resume later this month.