NEW YORK, Apr. 9 -- The U.S. Midwest prompt aluminum premium over London Metal Exchange cash prices remains at higher levels as metal availability continues to be tight.

Observers see the premium in a range between 6 cents and 6.5 cents, compared with similar levels early last month.

Lack of scrap aluminum availability is forcing consumers to seek out primary metal, some of which is tied up in warehouse financing deals, a situation making for higher premiums, said Mike Southwood, publications manager with CRU Group. He put the premium in the range of 6.0 cents to 6.5 cents.

"It's difficult to get metal out of warehouses because they're in financing deals," said a trader who can't be named because he isn't authorized to speak with the media. He said the premium is in a range from 6.1 cents to 6.25 cents.

He said he believes the premium will probably drift higher.

"Physical demand is improving," he says.

LME cash aluminum was officially quoted at $2,295.0 to $2,295.5 per metric ton Thursday, or about $1.0409 to $1.0412 per pound.

Inventories of aluminum stored in LME warehouses fell 4,700 metric tons to 4,586,125 from Wednesday to Thursday. The total is down from 4,594,300 metric tons one week ago.