UPDATE 1-Two Barcap metals traders exit after big losses

* Feb/Mar 2012 aluminium spread collapses

* Traders named as Iain Macrae, Christian Saunders

* No comment from Barclays

By Melanie Burton

LONDON, Dec 22 (Reuters) - Two senior metals traders are leaving Barclays Capital after it registered heavy losses on the London Metal Exchange (LME) aluminium and copper markets, industry sources told Reuters on Thursday.

The sources named the traders as Iain Macrae and Christian Saunders. Barclays declined to comment. The two traders could not be reached for comment.

The losses are said by traders to run into many millions of dollars and to stem from losing positions on the February-March 2012 aluminium spread on the LME. Copper options and spreads also lost Barclays money earlier this year, the traders said.

"I would think it is not only the failed aluminium, many other factors contributed," said another LME trader.

Several investment banks, including Barclays, in October began building large long aluminium positions into early 2012, trying to book profits during a tough year of unpredictable prices and dwindling consumer demand.

The banks were said by traders to be targeting those who have long-term financing deals on metal and hold it in warehouses. Owners of metal held in warehouses commonly hedge their positions by taking shorts position on the LME.

Since September, traders said Barclays had bid the February 2012 contract for aluminium up to a premium against March, but it dropped to a steep discount this week and Barclays was forced to liquidate the position.

The Feb-March spread traded as high as a $9-a-tonne premium on Dec. 5 and closed on Dec. 21 at a discount of $11.50 a tonne.

"We knew they were liquidating their nasty position," said an LME metals trader.

Traders said the bank had also lost money on copper options and spreads.