LONDON (Reuters) - Glencore's (>> Glencore PLC) powerful oil trading division is undergoing a rare reshuffle after 20-year veteran executive Louis Alvarez retired, while the former head of BP's (>> BP plc) Asian trading arm has been hired to head the firm's Singapore-based operations.

Hiring outsiders is a rarity for Glencore, which prefers to groom people from within, including current Chief Executive Ivan Glasenberg, who traded coal when Glencore's founder Marc Rich was in charge in the 1980s.

The changes come as Glencore has praised how its trading expertise can buffer results against the collapse in oil, metal and iron ore prices, with the firm emphasising its commodity dealing roots in its latest results.

Alvarez was the head of crude oil under Alex Beard, the long-serving global head of oil for Glencore. Alvarez retired at the start of 2015, a source close to the company and several trading insiders told Reuters.

Both men came from BP in the early 1990s and at the time of Glencore's landmark share placement in 2012, Alvarez was worth $600 million based on his shareholding in the company.

Glencore has now hired the head of Goldman Sachs's (>> Goldman Sachs Group Inc) commodity business in Asia to run its Singapore operations, two industry sources said on Monday, appointing a veteran fuel oil trader in the world's largest hub for the heavy fuel.

Chin Thean Quek, who once headed BP's Asian trading operation, had built a reputation as one of the most powerful traders in the Singapore-centred fuel oil market before joining Goldman two years ago.

Glencore already owns global fuel oil trader Chemoil, but firms have been focussing increased resources on the Singapore market, seeing opportunities after the collapse of Danish shipping fuel trader OW Bunker late last year.

Mark Catton, who headed Glencore's Singapore operations during an 18-year stint in Asia, is moving back to London, one of the sources said, without saying what new position he is taking at the commodity trader and miner. He has been with Glencore since 1990.

Quek, who left BP with his team to run China's Brightoil Petroleum in 2010, brings with him from Goldman a reputation for quickly establishing one of the largest fuel oil operations in Singapore, the world's hub for trading the heavy fuel.

Within two years of joining Brightoil his team was dominating the fuel oil derivatives market in Singapore, trading the equivalent of 17.3 million tonnes a year or more than double that of BP, its closest rival.

Brightoil also became the second-largest bunker supplier by volume in Singapore in 2011, according to the Maritime Port Authority of Singapore.

BP sued Quek and five other ex-employees in 2010 alleging they had taken confidential company information, including oil trading "cheat sheets". The team of six counter-sued BP for wrongful dismissal, saying it had withheld money owed to them.

To replace Quek, who joined Goldman two years ago, the bank has appointed Xiao Qin as the new head of its Asia commodities business, according to an internal memo seen by Reuters and confirmed by a spokesman for the bank.

Banks have faced increased regulatory pressure on their physical oil and metal trading activities, though Goldman has stuck with the multi-billion dollar business even as many rivals have pulled back.

Xiao, an options trading veteran, first joined Goldman 15 years ago. He left the bank for a stint at UBS before rejoining in 2008.

(Additional reporting by Silvia Antonioli; Editing by Mark Heinrich and Susan)

By David Sheppard and Dmitry Zhdannikov

Stocks treated in this article : Goldman Sachs Group Inc, Glencore PLC, BP plc