FACTBOX-Key risks to watch in Nigeria

(repeats piece first issued on March 9)

By Nick Tattersall

LAGOS, March 9 (Reuters) - Uncertainty over Nigeria's presidential succession, violence along a major ethnic fault line, and the risk of fresh unrest in the oil-producing Niger Delta are clouding an otherwise bright investment outlook.

Africa's most populous nation remains a compelling frontier market for foreign investors but its volatile political climate, which poses risks to everything from oil production to banking reforms, means many remain on the sidelines for now.

Following are some of the factors investors are watching.

PRESIDENTIAL SUCCESSION

President Umaru Yar'Adua returned from three months in a Saudi clinic on Feb. 24 but remains too sick to govern, raising fears of a power struggle as his inner circle tries to maintain influence and undermine Acting President Goodluck Jonathan.