Big money from the Middle East is still stalking the London Stock Exchange.

The Qartar Investment Authority, which is also preparing to buy J Sainsbury, the British supermarket chain, is said to be joining forces with three major Italian investors to take Nasdaq’s stake in the LSE, worth around £1billion ($2bn).

Nasdaq is selling its shareholding to increase its offer for Nordic exchange OMX, where it is in competition with another Gulf state, Dubai.

Nasdaq’s Robert Greifeld has put the American company’s substantial stake in the London Stock Exchange up for sale.

The move is thought to signal the end of the aggressive CEO’s ambitions to take over the LSE, while giving him extra leverage in his bid for the Scandinavian exchange group, OMX.

The sale would open the way for a higher offer on OMX, after the Dubai Financial Centre topped Nasdaq’s agreed bid last week.

Speculation is rife that a deal between Nasdaq and Dubai may be in the offing, which would leave the ambitious Gulf State with a major holding in the LSE and Greifeld with a clear run at OMX.

That would be yet another blistering headache for Clara Furse and her team in the City.

The Dubai stock exchange is seeking approval from the board of OMX, the pan-Scandinavian stock exchange group, to support a £2 billion ($4bn) takeover offer this week.

The Dubai International Financial Centre (DIFC), which owns the exchange, has set up meetings with key shareholders of the Swedish-based group and its management, to pave the way for a bid of around 230 kronor (£16.70) per share. Bankers at HSBC, which is advising the Dubai owners, seem to have suggested privately that the Emirate was prepared to pay as much as 250 kronor a share.

They will also have meetings with members of the Swedish government and regulators in an attempt to win support for the approach.

These moves could have implications for the London Stock Exchange. Dubai is thought to have plans to create a pan-European exchange to include the LSE and its new partner, Borsa Italiana. Such a grouping would rival NYSE/Euronext, which was formed last year.

Nasdaq’s recently-agreed bid of £1.8 billion ($3.6bn) for OMX now looks weak in comparison. However, talk of Dubai approaching the American exchange to be part of its masterplan seem wide of the mark. Dubai is shy of a political backlash if it buys in America again, following turbulence created by its recent purchase of P&O and its American ports.

Nasdaq chief executive, Bob Greifeld, last week told investors that its funding for the OMX bid was “flexible”. Insiders are apparently saying that “all options” were on the table, including selling some of Nasdaq’s 22 percent stake in the London Stock Exchange.

A source is quoted as saying, “Greifeld is determined to get this and is leaving no stone unturned. He is also aware that his future is uncertain if this bid fails, after the failure of the London Stock Exchange bid.”

With a place in the FTSE 100 now assured, Clara Furse may be on the prowl again for another asset to bolster LSE independence from Dubai’s predatory instincts.

The long-awaited counterbid for the Scandinavian stock exchange group, OMX, by the Dubai International Financial Centre (DIFC) could be made this week.

Advisers, UBS and Goldman Sachs are said to be on standby for the event.

The new bid is expected to be up to 20 percent higher than rival Nasdaq’s agreed $3.7bn (£1.9bn) merger offer already on the table.

DIFC is understood to have amassed a stake in OMX of around 4 - 5 percent in the open market, which is below the 5 percent level where a bid must be declared under Swedish rules.

A Dubai director recently said that “the sky’s the limit” for its international investment ambitions.