20100117

LONDON (Reuters) - London-based oil explorer Tullow Oil has exercised a right to buy Ugandan oil fields which its partner in the fields, Heritage Oil, previously agreed to sell to Italy's Eni for $1.5 billion.

A spokesman for Tullow said the company had served notice on Heritage on Sunday, potentially wrecking Eni's plan to build a new presence in Uganda.

Heritage and Tullow have found up to 2 billion barrels of oil in blocks around Lake Albert.

Heritage owns 50 percent of Block 1 and 50 percent in Block 3A. Tullow owns half-interests in Block 1 and 3A and also owns 100 percent of Block 2.

The three blocks cover the Uganda side of Lake Albert.

Tullow last year started a process to sell up to 50 percent of its own Ugandan assets, with a buyer expected to be selected early this year.

The spokesman said the Heritage assets will be included in the package being offered to potential partners. This should generate stronger buying interest in the sale process, analysts said previously of the plan.