The Nigerian opposition has made more gains in the final round of the country's election process.

The All Progressives Congress (APC) has retained the governorship in commercial hub Lagos and gained governorships in northern states Kaduna and Katsina.

Final results for 29 governorships and all 36 state assemblies are still being tallied.

Nigeria's governors control huge budgets and are among the country's most influential politicians.

The regional elections come two weeks after Muhammadu Buhari defeated incumbent President Goodluck Jonathan to become the country's first opposition candidate to win a presidential poll.

On Sunday, the Independent National Electoral Commission (Inec) announced that the general's APC had retained power in Lagos state.

When Gen Buhari takes over the presidency it will be the first time that the president's party will control Lagos since the end of military rule in 1999.

Nigeria's 36 governors enjoy wide powers and some control huge budgets

Inec have also announced that the APC have taken control of the governor's seats in Kaduna and Katsina from President Jonathan's People's Democratic Party (PDP).

The two northern states have been held by the PDP since the return of democracy in 1999.

The PDP candidate of north-eastern Adamawa has also issued a concession statement, although results in that state have not yet been finalised.

Irregularities

Nigeria's 36 governors enjoy wide powers and some, especially in oil-producing areas, control bigger budgets than those of national governments in some neighbouring West African countries.

Inec reported 66 violent incidents at polling stations during Saturday's elections. The highest number took place in oil-rich Rivers.

Voting has been extended in many parts of the state after irregularities at some polling stations.

Inec said that some ballot papers had been openly stolen.

Two weeks ago, observers generally praised the presidential election, though there have been allegations of fraud even with the use of biometric voting cards.