MOSCOW (Reuters) - Onexim Group, which manages the assets of Russian tycoon Mikhail Prokhorov, is considering selling some of its 17 percent stake in Russian aluminium giant Rusal (>> United Company Rusal Plc), two banking sources and two industry sources told Reuters on Thursday.

Reports of a possible share sale came on the same day two sources close to Rusal and a banking source told Reuters the Hong Kong-listed company was also considering listing in London.

Russian companies have seen a long-expected revival in investment demand this year amid signs of stabilisation in the country's economy situation after several years of crisis.

Three Russian firms have already raised a total of almost $800 million in share sales in 2017, in addition to a number of debt issues, including Rusal's own $600 million Eurobond.

"It is a good time for the share sale taking into account the high interest in Russian shares. However, maximum mutual benefit will only be reached if Onexim sells this stake via Rusal," said Kirill Chuyko at BCS Investment Bank.

All four sources said Onexim could start accelerated book building for the stake sale in the near future. According to one of the banking sources, Onexim is considering selling about 5 percent of Rusal.

Onexim declined to comment. Rusal was not immediately available to comment.

Earlier on Thursday, sources said Rusal was considering a London listing, with one saying the aluminium giant could offer up to 20 percent of its shares on the London Stock Exchange.

News that Rusal's executives and bankers have discussed selling up to a 20 percent stake in London was first reported by Bloomberg on Thursday, citing two people familiar with the matter.

"Rusal has a programme aimed at increasing liquidity (of its shares) and a listing in London is being considered as a part of it," another source close to Rusal said.

He said no decisions had been taken on timing, how much could be offered nor whether there would be new shares.

Rusal declined to comment on the reports of London listing plans.

Rusal competes with China's Hongqiao (>> China Hongqiao Group Ltd) for the rank of the world's biggest aluminium producer. Rusal's market value has jumped 30 percent so far this year helped by global aluminium prices, which have climbed 9 percent.

Russian tycoon Oleg Deripaska's En+ Group owns 48.1 percent of Rusal, with 15.8 percent owned by Viktor Vekselberg and Leonard Blavatnik's Sual Partners. Glencore (>> Glencore PLC) holds 8.75 percent and the remaining 10 percent is listed in Hong Kong.

Prokhorov's Onexim was in talks to sell a Rusal stake to Vekselberg last year but market and industry sources said this week those talks had stalled.

At the same time, Deripaska's EN+ is considering an initial public offering in 2017 and has already picked arrangers for the deal, financial sources have said.

(This version of the story clarifies paragraph 3 to say that the board is not considering such a move)

(Additional reporting by Katya Golubkova, Olga Popova and Andrey Kuzmin; writing by Alexander Winning, Katya Golubkova and Polina Devitt; editing by Greg Mahlich and David Clarke)

By Polina Devitt and Anastasia Lyrchikova