* Q3 premiums agreed by some buyers at 22-23 pct below Q2 numbers
* Further deals expected later this week as talks continue (Adds comments and details)
TOKYO, June 27 (Reuters) - Some Japanese aluminium buyers have agreed to pay producers a premium of $90 per tonne for metal to be shipped in the July-September quarter, two sources directly involved in the quarterly pricing talks said on Monday.
The deal, which marks a 22-23 percent fall from a $115-$117 per tonne premium PREM-ALUM-JP in the previous quarter, is the first drop since the October-December quarter of 2015, and is in line with a slide in overseas surcharges for physical aluminium.
Japan is Asia's biggest importer of aluminium and the premiums for primary metal shipments it agrees to pay each quarter over the London Metal Exchange (LME) cash price CMAL0 set the benchmark for the region.
"We struck a deal with a producer at $90 per tonne last Friday," a source at an end-user told Reuters, declining to be named due to the sensitivity of the talks.
Buyers in Japan are still negotiating with global producers, with further deals expected later this week.
Early this month, top aluminium producers offered Japanese buyers premiums of $100-$110 a tonne for July-September primary metal shipments, down 4-15 percent from the previous quarter.
But buyers countered at around $90-$95 due to weaker spot premiums in Asia, the United States and Europe, as well as because of higher inventories at home. stocks held at three major Japanese ports climbed for the first time in nine months in May due to an increase in imports amid softer demand at home.