The World Health Organisation says a diphtheria outbreak in war-torn Yemen has spread rapidly nationwide and infected more than 1,300 people.

The WHO said in a statement that children and young adults account for almost 80 per cent of cases and more than 70 people have died.

Diphtheria, first reported in Yemen in October last year, is a contagious and potentially fatal disease that primarily infects the throat and airways.

The WHO said on Friday that a vaccination campaign targeting 2.7 million Yemeni children has been completed in 11 governorates.

Yemen has been engulfed in a civil war pitting a Saudi-led coalition backing an internationally recognised government against Iran-backed Shiite rebels since March 2015.

The near three-year stalemated war has damaged Yemen’s infrastructure, crippled the health system and pushed it to the brink of famine.