Veteran Algerian diplomat Lakhdar Brahimi is expected to be appointed as the new UN-Arab League envoy for Syria, according to diplomats.

If confirmed, he would succeed former UN Secretary General Kofi Annan, who resigned last week saying he could no longer carry out the role, BBC reports.

A six-point peace plan proposed by Mr Annan failed to come into effect, and violence has escalated.

Rebels lost control of a key area of Aleppo after weeks of fighting.

The rebel Free Syrian Army (FSA) confirmed it had retreated from the strategic Salah al-Din district in the face of a large-scale government offensive launched the previous day.

Mr Brahimi's appointment could be announced as early as next week, barring last-minute objections from governments, diplomatic sources told journalists.

Mr Brahimi, 78, has held a long series of high-profile diplomatic posts.

As a senior Arab League official between 1984-91, he brokered an end to the Lebanese civil war, going on to serve as Algerian foreign minister between 1991-3.

Later, he was twice appointed as the UN's top envoy for Afghanistan, in 1996-8 and in 2001-4. He has held similar roles for Haiti and South Africa.