Over 7 million people are starving in Cameroon, Chad, Niger and Nigeria as a result of violence by the Boko Haram terror group, media reported.

Coinciding with a humanitarian conference in Oslo to mobilize funds for that region, the FAO on Friday noted that the situation has deteriorated "drastically" in the Lake Chad basin as instability persists, media reported.

The number of people affected by severe food insecurity has doubled to more than seven million, compared with 3.4 million in June 2015.

Among them are 515,000 children suffering from acute malnutrition, which if left untreated, can pose serious problems for their development and even lead to death.

FAO called for "swift and decisive" action by the international community to protect the lives of millions of families dependent on agriculture, livestock and fisheries.

"Our collective efforts cannot be limited to merely avoiding massive famine. They need to allow people to return to a dignified life. And supporting agriculture is the key to both," said FAO emergency director Dominique Burgeon.