* Delivers tents, blankets to stranded in Azaz
* Crossline operation called a "breakthrough"
* WHO reports leishmaniasis outbreaks in Aleppo, Deir al-Zor (adds details, WHO on disease outbreak)
By Stephanie Nebehay
GENEVA, Feb 1 (Reuters) - The U.N. refugee agency said on Friday that it had reached an opposition-held area of north Syria for the first time and found about 45,000 displaced people living in appalling conditions.
A senior U.N. official voiced fears that other parts of the country could contain similar untold stories of suffering and he said Syria faced systematic destruction.
The Syrian government agreed to give the U.N. access to the zone of Azaz north of Aleppo near the Turkish border, enabling a convoy to deliver tents and blankets to needy people living in the open in sub-zero temperatures.
"This is an area that the U.N. has not been able to physically reach ever since the beginning of the conflict," Yacoub El Hillo, director of UNHCR's Middle East and North Africa Bureau, told reporters in Geneva.
El Hillo, who was in Syria last week, added: "It is an appalling situation in Syria today. Probably all these figures are not capturing the true story of how Syria, the people but also the country, are facing systematic destruction."
U.N. supplies including food have reached Azaz, "a very far corner of the country" in the northwest from time to time, but via partner agencies and not U.N. staff. "People have been stranded, cut off without any systematic aid," he said.
"It is a breakthrough," UNHCR spokesman Adrian Edwards told Reuters.
Azaz is located opposite Kilis camp on the Turkish side that holds about 10,000 Syrian refugees who have crossed that border, according to the U.N. High Commissioner for Refugees (UNHCR).
"On this (Syrian) side it is makeshift camps in appalling conditions. So hopefully this will be the first of many, many convoys that we will be operating," El Hillo said.
UNHCR's 8-truck convoy delivered 2,000 tents and 15,000 blankets to Azaz after taking three days to reach the area from a civilian airport near Latakia on the Syrian coast, he said.
"They want us to continue, it could not have happened without the Syrian government. For the planes to land near Latakia we had to have landing permits and also for the trucks to move," El Hillo said.
"It is indeed our aim to move the next convoy in the new few days with larger quantities of aid to this population in that part of the country but also many other parts of the country where displaced families are today in disputed areas and not only in government-controlled areas."
The government of President Bashar al-Assad, locked in a two-year conflict, does not allow U.N. agencies to enter rebel-held areas from across its borders but agencies including Medecins Sans Frontieres have been active in Azazn, he said.
"It (the situation) is pushing us also to try everything possible to deliver aid from within Syrian territory in respect of Syria's sovereignty. The government's position is clear on cross-border deliveries."
Doctors in Aleppo and Deir al-Zor have reported outbreaks of leishmaniasis, an endemic tropical disease transmitted by sand-flies that causes skin ulcers resembling leprosy, the World Health Organization (WHO) said on Friday.
Poor waste management and lack of hygiene have fuelled its spread, but the U.N. agency is trying to deliver medicines to both hotspots, WHO spokesman Glenn Thomas told a news briefing.
Some 420,000 people, half of them children, need urgent humanitarian aid in Homs province, the U.N. Children's Fund said, reporting on an inter-agency mission to the central area.
"Almost one in three people in Homs is a displaced person and about two-thirds of the displaced are below 18 years old," UNICEF spokeswoman Marixie Mercado said.
The mission also visited opposition-held Talbiseh, about 30 km north of Homs, the scene of heavy fighting in the past year.
"Women are taking donated blankets and turning them into clothing, breaking up children's clothing sets so that they can get shoes to one child, a sweater to another child and pyjamas to another child," Mercado said.
(Reporting by Stephanie Nebehay; Editing by Stephen Powell)