UPDATE 1-Noble Group nets less than expected from oil unit sale to Vitol

(Adds detail on proceeds from combined oil, gas, power sales)

LONDON, Jan 15 (Reuters) - Struggling commodities trader Noble Group has completed the sale of its U.S.-focused oil business to the world's largest oil trader Vitol, but net proceeds from the deal are lower than a previously announced estimate, the company said on Monday.

In a statement, Noble Group said net proceeds from the sale of Noble Americas Corp (NAC) to Vitol were expected to be about $400 million.

In October, Hong-Kong based Noble said gross proceeds from the deal would be about $1.42 billion and it expected to make about $580 million after repaying loans.

Noble said the lower return on the sale that closed on Jan. 12 was "primarily due to operating losses of NAC from Oct. 1 2017 to the closing date."

The Singapore-listed company, which had a market capitalisation of $6 billion in early February 2015, was plunged into crisis after a report by blogger Iceberg Research later that month questioning its accounting.

Noble stood by its accounts and rejected the report's allegations but coupled with a major commodities downturn, the firm was unable to recover investor confidence.

Its market value has shrunk to around $200 million as it has progressively sold off large parts of its business to stay afloat.

Noble also sold U.S. gas and power business to Mercuria for less than previously announced - $168 million compared with $250 million.

Paul Brough, a restructuring specialist who oversaw part of the liquidation of Lehman Brothers, was appointed chairman last year and said he was taking steps to avoid insolvency.

The company has also been closing what remains of its global oil trading business, returning to its roots as an Asian hard commodities trader.

Noble said it had generated about $525 million in net proceeds after the sales to Mercuria and Vitol as well as monetising what was left of its oil business within UK incorporated Noble Clean Fuels Ltd.

On top of the approximately $400 million from the Vitol deal, the trader said it had "generated over $100 million of cash proceeds" from the wind down of working capital balances in NCFL, which was largely concluded in December 2017.

Included in the total was $20 million released from escrow to the group from the deal with Mercuria. (Reporting by Julia Payne; Editing by Mark Potter)