Food security in the Middle East and North Africa "is fast deteriorating" because of conflicts in countries from Syria to Yemen, the UN's food agency said Thursday.

Violence in nations that also include Libya, Iraq and Sudan are leading to "a widening gap in well-being" compared with other parts of the region, the UN Food and Agriculture Organization (FAO) said in a report.

"The level of undernourishment in the conflict countries is now six times larger than that in non-conflict countries," it said.

Yemen is suffering the worst food insecurity and malnutrition of all the conflict-hit countries in the region, followed by Syria and Sudan, it said.

For more than two years, Yemen has been locked in a devastating civil war between the Saudi-backed government and Huthi rebels who swept into the capital in 2014.

More than 8,750 people have been killed since a Saudi-led coalition intervened on the side of the government in March 2015.

Nearly a quarter of the population of Yemen suffers from severe food insecurity, according to the FAO.

Mark Lowcock, the UN under-secretary-general for humanitarian affairs, said in November that unless the coalition ends a blockade of the country, Yemen will face "the largest famine the world has seen for many decades, with millions of victims".

The FAO said the conflict-hit countries may not have sufficient resources to achieve the UN-adopted Sustainable Development Goals (SDG).

The goals include to "eliminate hunger, ensure food security, improve nutrition and promote sustainable agriculture" by 2030.

As "expenditures on violence crowd out other government spending, the likelihood of progress" on targets related to "reducing hunger and food insecurity and malnutrition becomes ever more remote," it said.

Between 21 and 67 percent of the conflict-hit countries' gross domestic product was spent on committing, containing or preventing acts of violence, or on dealing with their consequences, it said.

The FAO reported "elevated levels of stunting" in the region and said many of the poorer countries have severe levels of anaemia in children under five years old.