Alcoa Inc has used an aluminum price including benchmark futures and regional premiums that are similar to current levels for its 2015 free-cash flow forecast of $500 million, Chief Financial Officer William Oplinger said on Monday.

In its fourth-quarter earnings call, Oplinger declined to say what aluminum price the company used for its 2015 projects, but said they were "similar to the market situation that we have today".

That included the London Metal Exchange futures benchmark, regional premiums and currency effects.

His comments are likely to stir the debate over the direction of physical premiums, which are paid on top of futures for physical delivery and hit record levels.

"For North America, 2015 is set to be another good year for consumption as demand from the transport sector remains strong," Maquarie said on Tuesday in its 2015 outlook.

Many consumers say long wait-times to get metal out of storage and financing deals that take metal out of the market have kept premiums artificially high for years, while futures remain close to or below breakeven for many producers.

"It is worth remembering the tight market is more artificial than real given a huge amount of stocks sitting in warehouses both on and off exchange," Macquarie said, adding that the U.S. premium would be under downward pressure in 2015 as the volatility of LME spreads continue.

The Australian bank also said that it expected a slight global aluminum deficit in 2015, but "with the Chinese surplus expected to slightly widen".

Traders say premiums AL-PREM will come under pressure after the first quarter as logjams shrink due to changes in LME storage rules. They also say the low interest rates and wide forward price structure that make financing deals profitable will disappear.

Soaring premiums have provided support to producers since 2010 while LME prices have been under pressure amid soaring stockpiles.

Yet all-in prices may end up remaining the same, traders said, as futures prices rise to offset drops in premiums.

Also during the call, Chief Executive Officer Klaus Kleinfeld played down concerns about Chinese supply flooding the market, as it was unlikely that top producer and consumer China would remove an export tax for primary aluminum.

He added that the company was closely monitoring China's increased activity in the trade of semi-finished products.

LME benchmark three-month aluminum has fallen 10 percent since early December while regional premiums have hit record highs. (Additional reporting by Henning Gloystein in Singapore; Editing by Diane Craft, David Gregorio and Tom Hogue)