LONDON (Thomson Reuters Foundation) - More than half of war-battered Yemen's hospitals and clinics are closed or only partially functioning, the World Health Organization (WHO) said on Monday, warning a lack of adequate health services was increasing the risk of disease outbreaks.

Only 45 percent of 3,507 health facilities surveyed by WHO were fully functional and accessible, while more than 40 percent of districts faced a "critical" shortage of doctors, WHO said.

"These critical shortages in health services mean that more people are deprived of access to life-saving interventions," WHO said in a statement.

"Absence of adequate communicable diseases management increases the risk of outbreaks such cholera, measles, malaria and other endemic diseases."

The 18-month-old conflict between a Saudi Arabia-led coalition and the Iran-aligned Houthi group which controls much of northern Yemen has destroyed much of Yemen's infrastructure, killed more than 10,000 people and displaced millions.

UNICEF says the humanitarian disaster in the country has left 7.4 million children in need of medical help and 370,000 at risk of severe acute malnutrition.

Yemen's Health Ministry announced a cholera outbreak in early October in the capital Sanaa. By the end of the month, WHO said the number of suspected cholera cases had ballooned to more than 1,400.

In 42 percent of 276 districts surveyed by WHO there were only two doctors or less, while in nearly a fifth of districts there were none.

WHO said new mothers and their babies lacked essential ante-natal care and immunization services, while people suffering from acute or chronic conditions were forced to spend more on treatment or forgo treatment altogether.

(Reporting by Magdalena Mis; Editing by Ros Russell)