A series of airstrikes by the Syrian regime and its Russian allies hit the besieged rebel side of Aleppo on Thursday amid fierce ground fighting in the contested northern city, a monitor group and activists said.
The Syrian Observatory for Human Rights reported that the bombardment targeted the opposition-controlled neighbourhoods of al-Qalasa, Bustan al-Qasr and the Electricity Company in eastern Aleppo.
The Britain-based watchdog did not report casualties.
Heavy fightging was meanwhile raging along most battle fronts of Aleppo, especially in the south-western parts of the city, amid initial information about rebels' advances against regime forces, according to the Observatory's network of activists inside war-torn Syria.
Activist Ammar Jello, who is based near Syria's border with Turkey, said that at least 12 air raids by unidentified planes targeted a refugee camp near the town of Atareb in western Aleppo, killing at least two people.
At least 30 tents in the camp were destroyed, Jello told dpa by phone.
Syrian state radio said shells fired by rebels fell on the regime side of Aleppo, injuring dozens.
At least 16 civilians, including four children, were killed overnight in airstrikes by unidentified jets on rebel-held areas in Aleppo, the Observatory said.
In recent weeks, opposition activists have blamed intense air attacks on the eastern section on Syrian regime and Russian warplanes.
Last month, forces of Syrian President Bashar al-Assad imposed a siege on Aleppo's rebel-controlled districts after they blocked all supply routes into those areas, raising fears of a humanitarian disaster there.
Islamist rebels on the south-western outskirts of Aleppo, started on Sunday a major offensive on regime strongholds in the area in an attempt to break the regime blockade.
Once Syria's commercial hub, Aleppo has been divided between government forces in the west and rebels in the east since fighting erupted for control of the city in mid-2012.
Syria's conflict started in March 2011 with peaceful pro-democracy protests before devolving into a multi-sided war that has killed more than 250,000 people and triggered a global refugee crisis.
The World Food Programme (WFP) said Thursday it had completed an urgent relief operation to provide a one-month ration of desperately-needed food and hygiene supplies to more than 75,000 Syrians trapped along a land embankment at their country's border with Jordan.
The operation was launched in conjunction with the UN High Commissioner for Refugees, the International Organization for Migration and UNICEF.
"Unable either to cross the border or turn back, the situation facing these women, men and children has grown more dire by the day," the aid groups said in a joint statement.
"Sheltering in makeshift tents in harsh desert conditions with temperatures of up to 50 degrees Celsius and sudden sand storms, they are without sufficient food and have barely enough water to survive," they added.
Jordan declared its north-eastern and northern borders closed military zones, after a June suicide attack at an army base just across the border from Syria left seven Jordanian soldiers dead.
Jordan is home to more than 650,000 Syrian refugees, according to to the United Nations refugee agency.