LONDON (Reuters) - A court ruled in favour of Kurdistan-focused explorer Gulf Keystone (>> Gulf Keystone Petroleum Limited) in a case over its ownership of giant oil fields, removing a legal shadow hanging over the company and making it a more attractive to potential suitors.

In a packed courtroom, the judge on Tuesday dismissed claims made by Exalibur Ventures that it was entitled to a 30 percent share in the company's oil fields, bringing to a close almost three years of legal wranglings.

Gulf Keystone has long been touted as a takeover target for a big oil company looking for a foothold in Kurdistan, but the ongoing uncertainty created by the legal battle had been cited as a potential obstacle to any takeover deal.

The company's prize asset in Kurdistan is the Shaikan field, which is estimated to hold at least 12 billion barrels of oil - a volume which would make it one of the biggest discoveries made anywhere in recent years - and from which it aims to produce 250,000 barrels per day by 2018.

Kurdistan, a semi-autonomous region of Iraq locked in a dispute with Baghdad over oil exports and payments, was once the domain of smaller companies such as Gulf Keystone but recently big oil such as Exxon Mobil (>> Exxon Mobil Corporation), Total (>> TOTAL), Chevron (>> Chevron Corporation) and Gazprom (>> Gazprom OAO), have all moved in.

Excalibur's case was made against Gulf Keystone and Texas Keystone, a company founded by Gulf Keystone Chief Executive Todd Kozel, which holds a small interest in the Shaikan field in trust for Gulf Keystone.

Excalibur, a two-man company which said it helped introduce Gulf Keystone to the opportunity in Kurdistan, began legal action in 2010.

(Reporting by Sarah Young; Editing by Andrew Callus)