Syrian government forces clashed with rebels on the outskirts of eastern Aleppo city Sunday, a monitor said, after residents received messages from the army giving opposition fighters 24 hours to leave.

The Syrian Observatory for Human Rights, a Britain-based monitor, and an AFP correspondent in rebel-held east Aleppo reported clashes in the Karam al-Turab neighbourhood and the village of Al-Aziza just outside the city.

The AFP correspondent said the fighting could be heard in much of the rebel-held east, which is surrounded by government forces and has come under repeated assault since the army announced an operation to recapture it in September.

The fighting came as residents in east Aleppo received text messages warning rebels to leave within 24 hours.

"Gunmen in east Aleppo, you have 24 hours only to take the decision to leave," the message said.

"Those who want to save their lives must put down their weapons and their safety will be guaranteed. After the end of this period, the planned strategic offensive will begin," it added.

Syria's government and army have regularly sent rebels and residents in eastern Aleppo text messages warning them to leave the besieged sector.

Once Syria's economic powerhouse, the city has been divided into a government-held west and rebel-held east since mid-2012.

In September, the army announced an operation to recapture the east, unleashing a massive assault backed by Russian warplanes.

The initial phase of the assault killed hundreds of civilians and destroyed infrastructure including hospitals.

But in recent weeks, Russia has declared a series of brief truces, intended to encourage people to leave the east, although so far few have done so.

Rebels, meanwhile, have sought to break through government lines to end the siege on the east that began in July, so far without success.

They have fired barrages of rockets into western Aleppo, killing dozens of civilians, including four people in the Halab al-Jadida district on Sunday.

State news agency SANA said the dead included a child and two women.

Seven people were killed in regime rocket fire into Salhine district in east Aleppo, the Observatory said.

It said they died when a rocket hit the minibus they were in, and that the toll could rise because of the number of seriously wounded.

Another person was killed in artillery fire on Sukari district in the east.

More than 300,000 people have been killed in Syria since the conflict began with anti-government protests in March 2011.

Source: AFP