Algerian diplomat Lakhdar Brahimi is expected to be appointed as the new UN-Arab League envoy for Syria.
If confirmed, he would succeed former UN Secretary-General Kofi Annan, who resigned last week.
Diplomatic sources say Mr Brahimi's appointment could be announced this week.
The BBC reports Mr Brahimi, 78, has held a long series of diplomatic posts.
As a senior Arab League official between 1984 and 1991, he brokered an end to the civil war in Lebanon, before serving as Algerian foreign minister between 1991 and 1993.
Later, he was twice appointed as the UN envoy for Afghanistan, in the years 1996-98 and 2001-04. He has held similar roles for Haiti and South Africa.