Tens of thousands of people have been displaced in Aleppo as pro-government Syrian forces press on with their campaign to reclaim the divided city.

The Britain-based Syrian Observatory for Human Rights monitoring group said Wednesday more than 50,000 out of an estimated quarter-million inhabitants have been displaced by attacks on rebel-held eastern Aleppo over the past 4 days. Many of them fled to safer ground in areas under government or Kurdish control.

The International Committee of the Red Cross says around 20,000 people have fled.

The Lebanese Al-Manar TV channel reported from the Aleppo countryside that pro-government forces were advancing in the southern portion of the city's rebel enclave.

The government has seized much of the northern half of the enclave in a swift advance that began Saturday.