Poor harvest, sanctions further threaten Syria food supply -WFP
* Head of U.N. food aid body says watching situation closely
* More than 4 million Syrians currently receiving food aid
* Number set to rise to more than 6 million by year end
BRUSSELS, Sept 16 (Reuters) - Poor harvests and international sanctions have damaged Syria's ability to fund food imports and could sharply increase the number of people requiring food aid, the head of the U.N.'s World Food Programme said on Monday.
Syria's most recent wheat harvest was its worst in decades and traders say the country, mired in nearly three years of civil war, will need to import at least 2 million tonnes of wheat this year to help cover the shortfall.
While food purchases are not covered by Western sanctions imposed on President Bashar al-Assad's government, a financing freeze has hindered Syria's ability to import grain, sugar and other food staples.
"Because of the deteriorating crisis the agriculture system is being detrimentally impacted, and Syria is now having a challenge purchasing food on the international market," WFP Executive Director Ertharin Cousin told Reuters in Brussels.
"We are watching that very closely, because if that challenge escalates, that could dramatically increase the number of people inside Syria who require assistance from WFP."
The UN agency currently provides food aid to about 3 million people inside Syria, and a further 1.2 million Syrian refugees in countries including Jordan, Lebanon, Egypt, Turkey and Iraq. The total cost of the aid is about $30 million per week.
Cousin expects the number of people requiring food aid in Syria to rise to 4 million by the end of the year, with a further 2.5 million Syrians outside the country needing help. That would increase the operational cost to about $42 million a week, she said, making donor funds ever more essential.
Despite the massive humanitarian effort already under way, many Syrians remained trapped in areas with no access to aid due to heavy fighting between government and opposition forces.
"There are parts of Syria that we haven't been able to get in to for up to 10 months," she said.
"I'm often asked 'Who's fault is this? Who's stopping this?' It depends on what area you go to. Bullets don't say which side they came from, and it's the ongoing fighting that keeps us away," she said.
Since April, WFP has provided more than 23,000 tonnes of wheat flour to households in mainly rural areas to combat bread shortages following the poor harvest.
Cousin said the agency was also working to provide wheat flour to bakeries in urban areas, and hinted that it may increase deliveries in the coming months.
"Our goal is to evolve our delivery of support to meet the needs of the people that we're serving inside Syria. And if that means that we'll need to have more wheat flour, then yes, we'll have more wheat flour."
(Editing by Veronica Brown and Jason Neely)