...Heritage Oil Corp...said its ship was not at the center of a clash between Congolese troops and the Ugandan army on Lake Alberta, refuting earlier reports. The company also challenged a UN official, who told AFP the oil exploration vessel was escorted out of "Congolese waters" to "avoid increasing tensions" between the two nations and "to ensure the crew's safety." Earlier, a Ugandan army spokesman said two Congolese troops and a Ugandan soldier were killed in clashes Monday on the flashpoint border lake where oil was recently discovered. He said the clashes erupted when a military ship from the Democratic Republic of Congo intervened as Ugandan soldiers were seeking the release of an oil exploration vessel impounded by troops from the UN mission in Congo.