* Rio, South 32 seek Q2 premiums of $135/T
* Rusal raises its offer to $135/T from $125/T
* Japanese buyers aim at around $120-125/T (Adds details and quotes)
By Yuka Obayashi
TOKYO, March 8 (Reuters) - Three global aluminium producers have offered Japanese buyers a premium of $135 per tonne for shipments in the April to June quarter, up 42 percent from the previous quarter, three sources directly involved in the pricing talks said on Wednesday.
The offer, if accepted, would mark the second quarterly increase in a row. The higher offer comes as premiums rise in the United States and Europe and Japanese inventories are falling amid solid local demand.
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.
The latest quarterly pricing negotiations began last month between Japanese buyers and miners including South32 Ltd , Rio Tinto Ltd and United Company Rusal Plc, and are expected to continue through this month.
"We've received offers at $135 per tonne from South 32 and Rio Tinto," said a source at an end-user in Japan.
"Rusal has raised its offer to $135 per tonne this week from its previous offer of $125," he added.
In February, Rusal made an indicative offer of a premium of $125 per tonne to Japanese buyers for April-June primary metal shipments, according to sources.
South 32, Rio and Rusal were not immediately available for comments.
"The producers claimed that the rise mainly reflected higher premiums in the U.S. market, but we think $135 is too high as we don't feel much supply tightness here," another source at an end-user said, adding that his company would aim for premiums at around $120-125 per tonne.
U.S. and European spot premiums have risen by about $20 to $50 per tonne over the past few months, according to a source at a producer.
Aluminium stocks at three major Japanese ports fell slightly from the previous month to 273,100 tonnes at the end of January, but were down from 368,100 tonnes a year ago, according to trading house Marubeni Corp.
For the January-March quarter, Japanese buyers mostly agreed to pay a premium of $95 per tonne PREM-ALUM-JP, up 27 percent from the prior quarter.
Reporting by Yuka Obayashi; Editing by Christian Schmollinger