Swine fever has killed thousands of pigs in southwest Nigeria as the region has been hit by the worst outbreak in almost two decades, farmers said Friday.

The disease appears to have first broken out at a major farm housing some 2.5 million pigs outside the nation's economic hub Lagos. 

"The destruction is massive. We have lost almost everything. All the pigs... have died of Africa swine fever," farmer Labake Remi Makinde told AFP.

"The outbreak started in early February. The pigs are dying one after the other."

Adeze Ijenebe, leader of the local farmers association, said the problem was exacerbated by a coronavirus lockdown.

Farmers said they were now being forced to sell off their surviving pigs for well below the market rate and risked going out of business unless they received government help.  

"My fear is that something urgent should be done to avoid a spread," farmer Femi Kujembola told AFP.  

"Pork meat is rich in protein and to avoid scarcity and ensure food security, we have to protect the farmers."

In the past decade, swine fever has regularly surfaced in several parts of Africa. 

Between 2016 and 2019, more than 60 outbreaks were reported across the continent.

Nigeria has suffered repeated outbreaks but officials say the recent wave of infections is the worst by far.