HARARE (Reuters) - Zimbabwe's military has no say on who should take over from President Robert Mugabe, the country's army commander said, as tension mounts within the ruling party over who will succeed Africa's oldest leader.

Mugabe, 92, has held power since the country gained independence from Britain in 1980. But he is increasingly looking frail, stoking a scramble in ZANU-PF to succeed him.

Local media say some top military generals and a group within ZANU-PF are backing Vice President Emmerson Mnangagwa to succeed Mugabe. Another faction is widely believed to be maneuvering to impose Mugabe's wife Grace as a possible successor.

Lieutenant-General Valerio Sibanda, the Zimbabwe National Army Commander, told the state-owned Sunday Mail newspaper that the military should not get involved.

"In Zanu-PF the military has no role to play in terms of succession politics, and that is the long and short of it," he said, in his first comments on the succession issue.

Last year in December, Mugabe warned against the country's military generals and other security services supporting different candidates, saying it could ruin ZANU-PF.

Opposition parties accuse military commanders, who fought in the 1970s independence war, of working hard to ensure ZANU-PF remains in power.

On the eve of presidential elections in 2002 and 2008, military generals said they would not salute a leader who had not fought in the battle for independence. This was seen as an attack on main opposition leader Morgan Tsvangirai, who did not participate in the liberation struggle.

(Reporting by MacDonald Dzirutwe; Editing by Elaine Hardcastle)