(Adds U.N. confirmation, town resident comments, details)
BAMAKO, May 21 (Reuters) - Machine gun and heavy weapons fire broke out on Wednesday in the northern Mali town of Kidal, a rebel stronghold where the army has been reinforcing its positions ahead of an expected drive to retake it, an army officer and the United Nations said.
At least eight soldiers and eight civilians were killed during clashes between the army and Tuareg separatist that broke out on Saturday while Prime Minister Moussa Mara was on a visit to the town.
"As you can hear... gunfire has started up again between the soldiers and rebels in Kidal. I can't say more about it," the officer told Reuters by telephone from the town.
A spokesmen for Mali's defence ministry and the country's United Nations peacekeeping mission both confirmed that fighting had restarted but declined to give further details.
"From my room I hear heavy weapons fire. We were expecting this," said Kidal resident Mahamadou Maiga.
The clashes, which come a year after a French-led intervention drove out Islamist fighters, threaten to sink efforts to find a peaceful solution to the long cycle of Tuareg rebellions in the West African nation's desert north.
(Reporting by Adama Diarra; Additional reporting by Bate Felix in Dakar; Writing by Joe Bavier; Editing by John Stonestreet)