Demand for shares in Rosneft is set to reach as much as double those on offer, as about $18 billion of investors' money tries to clamber aboard the Russian oil group's bumper flotation set for Friday.

Demand from Russian, international and British financial investors is understood to have reached about $12 billion with just today to go before the investment banks running the share sale close the books on the deal.

Rosneft is aiming to raise as much as $11.6 billion in a controversial listing in London and Russia that should value it at more than £40 billion. A successful float of Rosneft would mark the biggest share sale on the London market for at least five years.

An indicative price range for the shares has already been set at $5.85 to $7.85 apiece. Achieving strong demand should help Rosneft set a price towards the top end of that range.

Boosted by yesterday's decision by the Financial Services Authority not to block the float, the deals lead banks - JP Morgan, Morgan Stanley, ABN Amro and Dresdner Kleinwort - have decided to close the books a day early, at 5pm today. The FSA's move to waive through the flotation is expected to prompt a rush of last-minute demand.

According to sources familiar with the matter, in addition to institutional buyers, strategic investors including trade rivals to Rosneft have applied for between $5 billion and $6 billion worth of the shares.

BP is reported to be among those groups that have decided to invest, although oil market sources maintained that no firm decision had yet been made.

Sources indicated that the Rosneft float is also going down a storm in Russia, where the shares are being made available to individual investors.

With orders currently running at about 24,000 a day, it is expected that Russian retail investors will have registered interest for about $500 million of shares.

The deal has proved controversial because of question marks over the acquisition of its main asset, Yuganskneftegas, from former owner Yukos.

Yukos has, so far unsuccessfully, tried to stop the Rosneft float on the grounds that a forced auction of the asset last year was illegal.

Once the books close at the end of the day, Rosneft's bankers will need a day to assess allocations and decide on a final price. This will be set for Friday morning, with conditional dealing to start that day.

As well as the four main banks that are joint global co-ordinators of the offering, a massive syndicate of about 25 further banks has been drafted in to manage the sale process.

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