LONDON (Reuters) — The London Stock Exchange has been left with few options to defend itself from Nasdaq Stock Markets Inc.'s unwanted attentions after British financial markets broker ICAP's decision not to pursue fresh merger talks, analysts said yesterday.Nasdaq is pressing ahead with a $2.7 billion ($5.1 billion) offer for Europe's largest share market, announced on Monday, despite the LSE having rejected it.

Sources familiar with the matter said the New York-based exchange has asked for the London Stock Exchange's shareholder register as it scrambles to send out its offer document, possibly as early as this week.

And analysts say the LSE is finding itself increasingly cornered, having already rebuffed four takeover approaches from rivals Deutsche Boerse, Euronext, Australia's Macquarie Bank and a previous attempt by Nasdaq.

"LSE has more limited means to counter this new bid than it had for the past offers," Elie Darwish, analyst at Exane BNP Paribas said in research note.

"We see no potential white knights for the LSE. As Nasdaq owns roughly 29 percent of the exchange it would be difficult for a third party to re-enter the race. LSE no longer has significant cash available to convince them not to support bidders."

The LSE plans to wait until it needs to issue its first defence document under UK takeover battle rules, which is 14 days after Nasdaq launches its offer, before starting its formal defence against the offer, the sources familiar with the matter said.

Meanwhile, Michael Spencer, the chief executive of ICAP, the world's biggest inter-dealer broker, said the company had no plans to re-engage in talks with the LSE.

ICAP had held discussions over a possible combination earlier this year.

"The LSE has done a very good defensive job, it's played a blinder. But the options for the LSE are narrowing," said Spencer.

Daniel Garrod, analyst at Citigroup, said Nasdaq's chances of success this time around were good, given the prospect of increased competition from the European stock markets' biggest users, investment banks, some of whom have clubbed together to set up a rival trading platform for European shares.

"This timing is opportune in that many LSE shareholders may be nervous about prospective threats from Project Boat (a plan by banks to report their own trades, taking revenue from the LSE) and Project European Multilateral Trading Facility and are looking for an exit," said Garrod.

Investment company Scottish Widows, a long-term holder of LSE shares, cashed in on a doubling in value so far this year on Monday, selling 7.07 million shares to Nasdaq at the US market operator's takeover offer price of 1,243 pence a share to give Nasdaq a total stake in the LSE of 28.5 percent.

Nasdaq said on Monday 1,243 pence in cash was its final offer although it reserved the right to revise the price if the LSE board recommended it or a rival bid emerged.

Dealers and analysts said the LSE board might be tempted to recommend an offer if it was increased to the 1,300 pence a share level and yesterday LSE's shares were trading for much of the day up 0.2 percent at around 1,294p.