MOSCOW -- The Russian military said Wednesday that fighting in Aleppo will cease for three hours daily to allow humanitarian aid deliveries, but it was unclear whether rebels had agreed.

A U.N. official, meanwhile, said a break in fighting for at least 48 hours was needed to get sufficient aid into the city.

Lt. Gen. Sergei Rudskoi of the Russian military's General Staff said the daily cease-fires will be observed from 10 a.m. to 1 p.m. local time starting Thursday. He didn't say whether the rebels have agreed to respect the halts in hostilities, or explain how they would be enforced.

Rudskoi says Russia supports the U.N. proposal to oversee the aid deliveries, adding that the Russian military is discussing the issue with U.N. experts and the U.S. military.

In Washington, U.S. State Department spokeswoman Elizabeth Trudeau said all parties to the Syrian conflict must abide by the U.N. request to ensure access for humanitarian supplies.

"We would welcome any pause that successfully facilitates delivering of vitally needed humanitarian supplies, but such a cease-fire must be observed by all parties," she said. "All supplies, including food and medical supplies, as determined and requested solely by the U.N., need to be delivered now."

Rudskoi told a briefing in Moscow that humanitarian convoys will be formed near Handarat and will move on the strategic Castello road.

At the United Nations, U.N. humanitarian chief Stephen O'Brien said that 48 hours and a two-lane road were the minimum requirement for getting sufficient humanitarian aid into Aleppo.

"When we're offered three hours, then you have to ask what could be achieved in those three hours?" he told reporters. "Is it to meet the need or will it only just to meet a very small part of the need? And clearly, from our point of view we're there to meet the need, all the need and we need to have sufficient capacity to do that."

The Syrian army won control of the Castello road last month, cutting the main supply link to rebel-held parts of Aleppo as government troops laid siege to the city. Opposition groups breached the siege over the weekend.

In Syria, state news agency SANA said insurgents shelled the government-held neighbourhood of Hamadaniyeh in Aleppo on Wednesday, killing at least 13 and wounding 25. Earlier in the day, opposition activists reported shelling and air raids on rebel-held parts of the city.

Rudskoi said the Syrian army backed by the Russian warplanes is now focusing on blocking rebel reinforcements from reaching Aleppo's southwestern outskirts as the Syrian troops have launched a counter-attack.

He said more than 1,000 rebels have been killed and about 2,000 have been wounded in the last four days of fighting in Aleppo. He said the militants also lost seven tanks, eight other armoured vehicles, 29 artillery pieces and 85 gun trucks. His claim couldn't be independently verified.