TOKYO, May 29 (Reuters) - A global aluminium producer

has offered Japanese buyers a premium of $175 per metric ton for

July-September primary metal shipments, up 18% to 21% from the

current quarter, three sources directly involved in quarterly

pricing talks said on Wednesday.

Japan is a major Asian importer of the light 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 a

premium of $145-$148 per ton , up 61% to 64% from

the prior quarter.

"The increase reflected tighter supply in Asia due to strong

demand from European customers," said a source at the producer,

noting that higher premiums in Europe were attracting global

producers to send supply to the region. He added premiums in

North America were also much higher than in Asia.

Japanese buyers, however, consider the level as too high

because demand in the country's industrial and construction

sectors remains sluggish and inventories are adequate, another

source at a Japanese trading house said.

The sources declined to be identified because of the

sensitivity of the discussions.

Aluminium stocks at three major Japanese ports

stood at 308,100 metric tons at the end of April,

according to Marubeni Corp ( MARUF ), higher than the 250,000

tons to 300,000 tons that are considered healthy.

Quarterly pricing negotiations began late last week between

Japanese buyers and global suppliers, including Rio Tinto Ltd ( RTNTF )

and South32 Ltd ( SHTLF ), and are expected to continue

until next month.