"Tullow Oil plc is pleased to announce that Tullow Uganda Ltd., its Ugandan subsidiary, has received judgment in its favor in the proceedings against Heritage Oil and Gas Ltd and Heritage Oil Plc in the Court of Appeal in London," Tullow said in a statement.
Heritage agreed to sell its Ugandan holdings to Italian energy company Eni in 2009. Tullow had the right to pre-empt the deal because of existing interest and in early 2010 the Ugandan government said it backed Tullow's plans despite a lobbying campaign by Eni to stop the transaction.
Tullow in April 2011 filed a claim in a British court claiming Heritage violated its sales contract by not reimbursing it for tax payments made to the Ugandan government
The London court ruled in Tullow's favor in all but one of the points appealed by Heritage, the company said.
"This point relates to part of one of Tullow's indemnity claims and will require Tullow to repay to Heritage approximately $2.5 million plus some interest," it said.
There was no statement from Heritage on the court's ruling.
The Lake Albert basin in Uganda has a target output of 200,000 barrels of oil per day.