By Chris Arsenault

ROME, March 3 (Thomson Reuters Foundation) - The Food and Agriculture Organisation (FAO) has launched an emergency appeal for $697 million to help 30 million people in 31 crisis-hit countries, a senior official with the U.N. agency said on Tuesday.

Somalia, Syria and countries in the Sahel region of Africa are some of the areas requiring the greatest assistance to boost agriculture and mitigate hunger, said Dominique Bourgeon, director of FAO's emergency division.

"We are trying to promote risk management, early warning systems and prevention (of food emergencies)," Bourgeon told the Thomson Reuters Foundation.

In Somalia, where the FAO has requested $118 million, the largest requirement for a single country, people are "on the edge", Bourgeon said.

"If there is a small drought, resilience collapses and the situation becomes desperate," he added.

Stopping or mitigating a crisis before it spirals out of control with support for farming is often more efficient than providing emergency relief, he said.

The FAO request - aimed primarily at helping farmers and people living in rural areas in regions hit by conflicts or natural disasters - constitutes about four percent of the United Nations' appeal for $16.4 billion to address humanitarian needs around the world in 2015.

Announced in December, the U.N. appeal aims to help more than 57 million people in 22 countries. The amount called for in 2015 is 27 percent higher than in 2014, due partially to violence in Syria, Iraq and South Sudan.

Bourgeon said in the past few years, donors aiding Syria largely saw the crisis as a temporary emergency.

Now many governments "realise the crisis is here to stay" and want to try and support what is left of the country's agricultural sector to ensure remaining farmers stay on the land, he said.

Of the 805 million people worldwide who suffer from chronic hunger, 129 million live in areas affected by protracted crisis and 79 million are highly vulnerable to natural disasters.

The FAO received about half of the emergency funding it requested last year, Bourgeon said.

Funds raised in 2014 were used to buy water tanks in the Gaza strip, vaccinate livestock in South Sudan, provide chickens in Iraq and rehabilitate wells in Djibouti among other projects.

(Reporting By Chris Arsenault, Editing by Katie Nguyen)