LONDON, Aug 12 (Reuters) - Prices of aluminium premium

contracts on Comex exchange beyond August have fallen due to

some speculation that tariffs on U.S. imports of the metal could

be halved or that top supplier Canada could get an exemption.

Taxes on aluminium are part of a broader U.S. effort to

revive domestic smelting capacity and cut reliance on imports of

the metal used in the transport, packaging, power and

construction industries.

Aluminium shipped to the United States has been subject to a

50% levy since June 4. The physical price premium for the August

contract has climbed above 70 U.S. cents a lb or $1,543 a metric

ton, up nearly 90% since the end of May.

U.S. buyers of aluminium on the physical market typically

pay the London Metal Exchange benchmark plus the Midwest

premium to cover costs including freight and taxes.

Traders and industry sources said the premium on Comex, part

of the CME Group ( CME ), for September onwards had dropped

because of bets on lower prices due to some expecting President

Donald Trump to row back on aluminium import taxes.

The Midwest aluminium premium for September is

currently trading around 67 cents a lb and at 60 cents a lb for

December.

Numbers from information provider Trade Data Monitor show

the United States imported more than 3.9 million tons of

aluminium last year of which 70% or more than 2.7 million tons

were shipped from Canada.

However, consultancy Harbor Aluminum expects tariffs on U.S.

aluminium imports to stay because the U.S. government believes

that tariffs are important for national security.

"Harbor does not see the U.S. reducing the 50% tariff or

offering exemptions ... more so now that it has become

'addicted' to the revenue the tariffs provide," the consultancy

said in a note.

"We remain bullish and continue to expect the Midwest

premium to trend toward 78 cents a lb before the end of the year

and 87 cent a lb in 2026."