Aug 23 (Reuters) -London aluminium prices inched higher on Friday and were poised for their biggest weekly gain since mid-April, buoyed by tight supply of raw material and expectation of a U.S. interest rate cut next month.

Three-month aluminium on the London Metal Exchange CMAL3 rose 0.2% to $2,484.50 per metric ton by 0128 GMT, while the most-traded October aluminium contract on the Shanghai Futures Exchange SAFcv1 eased 0.1% to 19,805 yuan ($2,772.26) a ton.

On a weekly basis, LME aluminium was up 5% and set for its best gain since the week of April 15. SHFE aluminium was also set for a weekly gain.

Strong demand for alumina and tight supply of bauxite, the ore form of aluminium, have underpinned prices, which hit a more than six-week high of $2,531 a ton on the LME on Thursday.

The discount of LME cash aluminium to the three-month contract CMAL0-3 tightened to $17.08 a ton, the smallest discount since May 1, indicating tightening nearby supply.

LME aluminium inventory has dropped 22% in three months to 877,950 tons, the lowest since May 8.

U.S. Federal Reserve policymakers on Thursday lined up in support of starting interest rate cuts next month. Fed Chair Jerome Powell is due to speak later on Friday.

Lower interest rates could soften the dollar and make greenback-priced metals cheaper to holders of other currencies.

LME copper CMCU3 rose 0.3% to $9,155.50 a ton, nickel CMNI3 rose 0.3% to $16,645, zinc CMZN3 advanced 0.5% to $2,871.50, lead CMPB3 increased 0.9% to $2,071.50 and tin CMSN3 was up 0.6% at $32,520.

SHFE copper SCFcv1 eased 0.7% to 73,480 yuan a ton, nickel SNIcv1 dropped 0.8% to 129,180 yuan, lead SPBc1 shed 1.1% to 17,345 yuan, while zinc SZNcv1 rose 0.9% to 23,865 yuan and tin SSNcv1 edged up 0.3% to 266,900 yuan.

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Reporting by Mai Nguyen in Hanoi; Editing by Subhranshu Sahu

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