Updated

Uganda's military says its troops have joined forces with the South Sudanese military in the war against a rebellion in the world's newest country.

Military spokesman Lt. Col. Paddy Ankunda said Thursday that Ugandan forces were helping loyalist forces flush rebels out of Bor, the strategic town near the capital of Juba that has seen some of the fiercest clashes since violence broke out in South Sudan in mid-December.

Ugandan officials had previously denied that its troops have joined the fight, saying Ugandan forces were deployed in South Sudan mainly to facilitate civilian evacuations.

The involvement of a foreign army in South Sudan's conflict could escalate a crisis set off by a power struggle between President Salva Kiir and Riek Machar, the fugitive former deputy president who commands rebel forces.