A convoy of trucks brought one month's food supplies for 12,500 people and wound-dressing material for up to 1,000 injured, depending on the severity of their wounds, the International Committee of the Red Cross said in a statement.

"Despite the difficult security conditions, the convoy managed to get inside the city," ICRC spokesman Hicham Hassan told Reuters.

"The assistance reached the city proper and will be dispatched by the Syrian Arab Red Crescent, which is working to assist thousands of people staying in 80 schools around Aleppo."

Uprooted families have gathered in crowded shelters in the northern commercial hub, which rebels say government forces have pounded with artillery and attack helicopters.

The ICRC temporarily evacuated some of its expatriate staff in Syria two weeks ago and most of its 50 aid workers currently deployed have been confined to Damascus since the conflict deepened in late July.

Until Thursday, it had been unable to send supplies to Aleppo as its minimum security requirements were not met, despite a mounting need for humanitarian aid, Hassan said.

"The assistance goes to civilians in all areas that the ICRC and Syrian Arab Red Crescent can reach, without distinction."

President Bashar al-Assad named a new prime minister on Thursday to replace Syria's most senior government defector as his forces pushed rebels back from the strategic district of Salaheddine in Aleppo.

The Syrian Arab Red Crescent was forced to suspend most of its activities in Aleppo two weeks ago due to "extreme danger on the ground", but dozens of its volunteers continue to work under difficult conditions, said Marianne Gasser, head of the ICRC's delegation in Syria.

Needs in other parts of Syria remain great, including in the city of Homs where thousands of displaced have taken shelter in schools and other public buildings, according to the ICRC.

The agency delivered a one-month supply of food for more than 20,000 in Homs last week and installed a generator to boost the capacity of a pumping station supplying 80 percent of the drinking water for the city's 800,000 residents and displaced.

Many of the main drugmakers in Syria have closed down, causing severe shortages of medicines for treating chronic diseases and a rising number of casualties, the World Health Organization (WHO) said on Tuesday.

"Many health care facilities are also finding it ever more challenging to treat the injured because their services have been disrupted by the violence, and medical items are scarce," the ICRC said on Thursday.