Administrators for failed Icelandic bank Kaupthing are looking to sell off British high street retailers including Coast, Oasis and Warehouse which employ thousands of people, four sources familiar with the matter said.

The bank was nationalised during Iceland's 2008-2011 financial crisis, with its domestic operations spun into a new bank known as Arion Banki, while all non-Icelandic assets remained with the now defunct Kaupthing.

Kaupthing acquired the brands in 2009 from Mosaic Fashions, which went into administration after shareholder Baugur collapsed in the wake of the crisis. Baugur owed most of its debts in Mosaic to what was then Iceland's largest bank.

The administrators are also looking at options for the more upmarket Karen Millen brand, two of the sources said.

Reykjavik-based Kaupthing, which filed for bankruptcy in 2008 and whose former executives were charged with fraud, did not respond to requests for comment, while the retailers were not immediately available for comment.

Kaupthing invited banks to pitch late last month for a mandate to auction the retail assets early next year, the sources said, but could face a tough sell.

Valuations of clothing retailers have come under pressure, with Britain's fashion market suffering its steepest decline in sales since 2009 as consumers increasingly spend their money elsewhere, according to industry data published last month.

A sale of Oasis, Warehouse and Coast could be worth less than 100 million pounds, two of the sources told Reuters. One of them said it might draw interest from private equity funds.

However, the funds may find it hard to submit competitive offers due to the poor outlook for British retailers, who have been further challenged by the fall in the pound since Britain's vote in June to leave the European Union.

In a bid to revamp Oasis and Warehouse, which now operate as one entity with separate shops, the brands hired new executives, launched new websites and logos in recent years.

Prior to being dismantled, Kaupthing owned the brands through holding company Aurora Fashions.

Filings with Britain's Companies House say that as of the end of February 2015, Aurora, which then included Oasis, Coast, Warehouse and Bastyan, employed some 5,422 people and made an annual loss of 14 million pounds. No up-to-date accounts were available.