Jana Partners, a US hedge fund manager, has launched a $1.8bn (€1.4bn) bid for Houston Exploration, a publicly-traded US oil explorer, in what would be one of the first direct takeovers of a public company by a hedge fund.

Jana said in a letter filed with the Securities and Exchange Commission: "Jana Partners owns 12.3% of the outstanding shares of The Houston Exploration Company. We wish to purchase the company at a price of $62 per share in cash."