Shares in oil explorer Heritage Oil (LSE: HOIL) rose more than 6% to 304.9p on Wednesday following rumours of a bid for the company or its assets.
The increase came despite British gas firm BG Group (LSE: BG) denying that it was interested in the company.
"We do not comment on market rumours or speculation but Iraq does not form part of BG's current plans," a BG spokesman told Reuters.
Austrian energy group OMV, which is part of the Nabucco consortium, has also been mentioned as a possible buyer for of all or part of Heritage.
(Sources: Reuters, Guardian)