By Scott Haggett

CALGARY, Alberta (Reuters) - Talisman Energy Inc <TLM.TO> <TLM.N> shares surged in after-hours trading on Monday after activist investor Carl Icahn said he had purchased about 61 million shares of the underperforming Canadian oil producer and may seek a seat on the company's board.

Talisman's New York Stock Exchange-listed shares surged 10.9 percent in after-hours trading after Icahn revealed his holding which gives him a stake of about 6 percent in the company. The stock closed at $12.75 in New York on Monday.

Icahn, a 77-year old billionaire, said in a filing with the U.S. Securities and Exchange Commission that he intended to talk with Talisman's management to discuss strategic alternatives for the company, include asset sales or restructuring. He may also seek a board seat, according to the filing.

The purchase, which makes him the company's second-largest shareholder, is the latest in the energy sector for Icahn. He was at the center of a 2012 boardroom coup at U.S. oil and gas company Chesapeake Energy Corp <CHK.N> that eventually led to the ouster of its free-spending co-founder Aubrey McClendon.

The activist shareholder also successfully pressed for management changes at the world's largest drilling contractor, Transocean Ltd <RIG.N>. In May, Transocean shareholders voted out Chairman Michael Talbert and backed an Icahn nominee.

Icahn also recently made headlines for his failed attempt to block Michael Dell's $25 billion bid to take Dell Inc <DELL.O> private as well as his efforts to prod Apple Inc <AAPL.O> Chief Executive Tim Cook to buy back $150 billion of stock.

Talisman's stock has gained 2 percent over the past 12 months but much of the rise has come since the start of the month, when rumors that an activist investor was buying began to swirl.

Talisman said that it takes the views of shareholders seriously but did not say if it would enter into talks with Icahn.

"We are committed to acting in the best interests of the Company and give due consideration to constructive recommendations for strategies or actions that have the potential to increase shareholder value," Phoebe Buckland, a spokeswoman for the company, said in a statement.

Talisman is already in the midst of a restructuring program led by Chief Executive Hal Kvisle, a board member and former head of TransCanada Corp <TRP.TO>.

The company, like other natural gas producers, is struggling to cope with weak prices as surplus production from prolific shale-gas fields floods the North American market. To cope, it has reduced overhead and expenses, including cutting 7 percent of its head office staff, and is focusing on producing more-profitable oil and natural-gas liquids.

Since stepping into the role following the abrupt departure of John Manzoni last year, Kvisle has put a host of assets on the block, including the company's holdings in Norway's North Sea, some Canadian shale-gas fields and its stake in Colombia's Ocensa pipeline.

(Additional reporting by Anna Driver in Houston and Michael Erman in New York; Editing by Eric Walsh and Phil Berlowitz)