(Adds details; updates share price)
* Analysts expect offers to be at or above C$3.35/shr
* Board to hold discussions with interested parties
* London-listed shares close up 14 percent
* Toronto-listed shares rise 11 pct
By Brenton Cordeiro
March 1 North Sea-focused oil and gas explorer Ithaca Energy Inc said it had received unsolicited interest from several parties, which analysts estimate could result in a deal valued at about C$868 million ($880.2 million).
The company's board would hold discussions with the interested parties, Ithaca said in a statement, but added that the discussions were still at a preliminary stage.
In January, Ithaca Energy said that it had received a confidential proposal to acquire all of its outstanding shares from an unnamed buyer, without disclosing any financial details.
Analysts expect an offer at or above C$3.35 per share -- 18 percent higher than its Wednesday close of C$2.84 on the Toronto Stock Exchange. The shares rose 11 percent to a near four-year high of C$3.15 on Thursday morning in Toronto.
An offer of C$3.35 per share would value the company at about C$868.2 million.
Ithaca's London-listed shares closed up 14 percent.
"We believe Ithaca's appeal to potential acquirers is its strong production growth potential from an operated asset base, supported by existing strong cash flows and a clean balance sheet," James Hosie of RBC Capital Markets said.
The likely bidders include British oil firm EnQuest, Abu Dhabi National Energy Co and privately owned Dana Petroleum.
"The company has a good line-up of future catalysts as well," GMP Securities analyst Jamal Orazbayeva told Reuters. "It offers good production growth, has a good management team and a good track record."
For the nine months ended September 2011, Ithaca's oil sales volumes were 2,002 barrels per day.
The company declined to comment beyond Thursday morning's press release.
Oil and gas production in the UK North Sea has passed its peak, as the larger and easier-to-tap deposits have been pumped out. But geologists say there are still billions of barrels left to produce in smaller accumulations.
Investment by energy companies in the North Sea in 2012 is expected to exceed last year's record of 7.5 billion pounds, and is expected to stay consistently high until at least 2014.
The North Sea has garnered a lot of interest with companies like Apache Corp buying North Sea Beryl field and other assets from Exxon Mobil Corp for about $1.75 billion. Other companies like Eni and Endeavour International have also bought assets there.
Ithaca -- engaged in the exploration, development and production of oil and gas in the North Sea -- said it had retained CIBC World Markets as its adviser. ($1 = 0.9862 Canadian dollars) (Reporting by Brenton Cordeiro in Bangalore, additional reporting by Eileen Anupa Soreng and Aftab Ahmed; Editing by Roshni Menon, Maju Samuel)