GENEVA (Reuters) - Areas of northeast Nigeria rendered inaccessible by an Islamist insurgency may be experiencing famine, an aid agency report said.

The United Nations estimates that almost 1 million people are in hard-to-reach parts of the northeast, where Islamist group Boko Haram has waged an insurgency for the past nine years.

The Famine Early Warning Systems Network (FEWSNET) said there was “an elevated risk of famine” in that area.

That means that famine “cannot be confirmed nor disproven with available evidence,” according to FEWSNET, which is funded by the United States Agency for International Development.

“There is insufficient evidence to make a formal determination,” it said in a report dated March 2 and seen by Reuters on Monday.

The insurgency has killed tens of thousands of people and displaced more than 2 million others, many of whom are almost entirely dependent on international aid.

“Remote internally displaced person settlement areas could, in a worst-case scenario, become cut off by violence and experience extreme food insecurity,” said FEWSNET.

Last week, suspected Boko Haram militants killed at least 11 people in a northeast Nigerian town, including three aid staff, in one of the first major attacks on humanitarian workers in the conflict.

Three other aid workers are missing and feared abducted.