LAGOS (Reuters) - A third of 743 health facilities have been destroyed in northeast Nigeria’s Borno state, the area worst hit in a seven-year insurgency by Islamist Boko Haram militants, the World Health Organization said on Wednesday.

The jihadist group has killed 15,000 people and displaced more than two million from their homes during its attempt to create a “caliphate” in the northeast of Nigeria, Africa’s most populous nation and biggest energy producer.

Nigerian military forces backed by troops from neighboring states have, in the last few months, ousted Boko Haram from most of an area the size of Belgium that they controlled until early 2015, revealing thousands living in famine-like conditions.

Boko Haram no longer holds much territory, having been pushed back to its stronghold in the Sambisa forest, but still carries out shootings and bombings in the region. On Friday, 56 people were killed in a suicide bomb attack by two girls.

The WHO said it had worked with Borno’s health ministry to gather information about medical services available there.

It said that of 743 health facilities, 35 percent had been completely destroyed, another 29 percent partially damaged and 34 percent remained intact.

Wondi Alemu, WHO’s Nigeria representative, said “high insecurity, difficult terrain and lack of health workers, medicines, equipment and basic amenities such as safe water” made it hard for people to access health care.

On Tuesday, the U.S.-based Famine Early Warning Systems Network said that at least 2,000 people may have died of famine this year in parts of northeastern Nigeria.

The United Nations has said 75,000 children could starve to death in the region over the next few months if they do not receive humanitarian assistance.

The U.N. has doubled its humanitarian funding appeal for northeast Nigeria to $1 billion in 2017 in an attempt to reach nearly 7 million people in the region who it said need life-saving help.