TOKYO : A global aluminium producer has sought a premium of $260 per metric ton from Japanese buyers for April-June primary metal shipments, up 14 per cent from the current quarter, two sources directly involved in pricing talks said this week. Japan is a major Asian importer of the metal and the premiums for primary metal shipments it agrees to pay each quarter over the London Metal Exchange cash price set the benchmark for the region. For the January-March quarter, Japanese buyers agreed to