Beijing - More melamine-tainted milk powder, which caused the deaths of six children in 2008, has been found in a northwestern dairy plant, once again raising concerns over poor supervision and management of food safety.

However, whether the 64 tons of problem products seized from a dairy plant in Qinghai province in late June were leftovers from the original batches of melamine-contaminated milk powder remained under investigation, the provincial quality watchdog said.

Six children died and 300,000 were sickened in 2008 from the contaminated milk.