TOKYO, May 30 (Reuters) - A major aluminium producer has offered Japanese buyers a premium of $110 per tonne for July-September primary metal shipments, down 4-6 percent from the previous quarter, three sources directly involved in pricing talks said on Monday.

Japan is Asia's biggest importer of the metal and the premiums for primary metal shipments it agrees to pay each quarter over the London Metal Exchange (LME) cash price set the benchmark for the region.

For the April-June quarter, Japanese buyers agreed to pay producers a premium of $115-$117 per tonne (PREM-ALUM-JP), up about 5-6 percent from the prior quarter, due to lower local inventories.

The latest quarterly pricing negotiations began late last week between Japanese buyers and miners including Rio Tinto Ltd , Alcoa Inc and South32 Ltd, and are expected to continue in June.

(Reporting by Yuka Obayashi; Editing by Richard Pullin)