The governor of Nigeria's Kaduna state, Patrick Ibrahim Yakowa, was killed on Saturday when his helicopter crashed in the southerly oil-producing Bayelsa state, an aide to the politician told Reuters.
Bayelsa police spokesman Fidelis Odunna confirmed a helicopter had crashed in Ogbia Creek but gave no details of who was on board or any casualties.
An aide to Yakowa who asked not to be named said Yakowa had been killed in the crash.
Nigeria's 36 state governors are among the most powerful politicians in Africa's biggest oil producer, often controlling budgets bigger than other African countries.
Local residents said several high-profile politicians had traveled to Bayelsa, President Goodluck Jonathan's home state, this weekend for a funeral. Jonathan was not in Bayelsa at the time of the crash, the presidency said.
Like many African countries, Nigeria has a poor air safety record.
Nigeria's deputy police chief and three other officers were killed when a helicopter crashed in the central city of Jos in March.
In June, a passenger plane crashed into a densely populated part of Lagos, Nigeria's commercial hub, killing 163 people.