BEIRUT — Amnesty International said Thursday the Syrian government has used internationally banned cluster munitions in attacks on a besieged rebel-held suburb of Damascus, accusing it of committing war crimes on “an epic scale.”

Eastern Ghouta, a rebel-held suburb northeast of the Syrian capital, has been under a tightening siege since 2013 and is already facing a humanitarian crisis, including the highest recorded malnutrition rate since the country’s civil war began in 2011. Some 400,000 civilians, half of them children, are believed trapped there. Amnesty said at least 10 civilians were killed in November.