UPDATE 1-Ex-VP Abubakar named opposition challenger to Nigeria's president

Atiku Abubakar won a primary race to become the main opposition challenger to Nigerian President Muhammadu Buhari in elections next year, results showed on Sunday.

Abubakar, a former vice president, will stand as the Peoples Democratic Party (PDP) candidate. At a party convention on Saturday, the ruling All Progressive Congress (APC) picked Buhari, who took office in 2015, for the February vote.

The handling of the economy has already emerged as a major issue at the start of the election cycle in Africa's top oil producer, which also plays a key role in regional wars against Islamist insurgents.

Nigeria entered its first recession in 25 years in 2016, mainly caused by lower oil prices and attacks in the Niger Delta crude-producing region. It emerged from the recession early last year but growth remains sluggish and inflation has remained high, above the central bank's single-digit target range.

Abubakar, 71, was selected in the PDP's primary election after the party held a convention in the southern city of Port Harcourt in the Niger Delta oil production heartland. 

(With inputs from agencies.)