William L. Transier, the company's chairman, chief executive officer and president, said it continued to be disappointed by the dislocation between underlying asset values and its share price.

'Last year, Endeavour sold just 19% of its reserves for $150m, which was more than the market capitalization of the company at that time.

'Since then, our stock price has traded back to pre-sale levels even though we believe the value of our remaining asset base represents a multiple of the existing share price.'

In an effort to unlock the value of its North Sea assets, Endeavour will study a range of options.

These include continuing to execute its current operations plan, entering a joint venture to accelerate activities in the North Sea, and selling specific assets or the entire North Sea business.

Transier added, 'We have believed for some time that the discount in our stock price was related to the length of time between discovery and production and the relatively high development costs in the UK.

'Our entry into the US onshore arena balances this position with an inventory of properties that can be developed in a much shorter time period and at lower cost.'