(Adds details from press release, updates share movement)
July 30 (Reuters) - Russia-focused oil producer Exillon Energy Plc said it has been approached by founder and former chairman Maksat Arip about a possible offer for the company, sending its shares up as much as 18 percent.
The Kazakh businessman is the company's largest shareholder with a 30.17 percent stake.
The company, which has assets in Russia's oil-rich regions of Timan-Pechora and western Siberia, said talks were at an early stage and Arip had to state whether or not he would make an offer by 5 pm on Aug. 27, as per UK takeover rules.
Exillon, which floated in London in December 2009 was fined nearly 300,000 pounds ($460,500) in April 2012 for failing to disclose payments made to Arip. He was chairman between November 2009 and April 2011. (r.reuters.com/san99t)
Worldview Capital Management, Exillon's biggest institutional shareholder, called for a management overhaul in January amid what it called "significant underperformance", but later withdrew a request for a shareholder vote.
Worldview Capital held a 15.12 percent stake in Exillon, as of June 30, according to Thomson Reuters data.
Exillon shares were up 11.8 percent at 143.5 pence at 1524 GMT on the London Stock Exchange on Tuesday.
The stock has been trading mostly below its listinig price of 153 pence for more than a year.
The company had a market capitalisation of 205.69 million pounds ($315.72 million) based on its closing price on Monday. ($1 = 0.65 British pounds) (Reporting by Karen Rebelo in Bangalore; Editing by Joyjeet Das)