* Sunni refugee influx sensitive issue in divided Lebanon
* Officials call first U.N.-run camp a "transit site"
* U.N. hopes for 17 similar sites
By Oliver Holmes
ARSAL, Lebanon, Nov 29 (Reuters) - White tents with "The U.N. Refugee Agency" written on them flap in the wind outside the Lebanese mountain town of Arsal. Children run past latrines and water points. In all respects, it is a refugee camp, but you must not call it that, say officials.
The site is home to about 350 people who have fled the civil war in neighbouring Syria - the first officially U.N.-run plot set up for displaced Syrians in Lebanon, complete with running water, toilets and other services.
But in a sign of the extreme sensitivities over refugees in the Mediterranean state, the authorities are doing all they can to play down any suggestion it is a settled facility for long-term residents.
"It's not a camp, it's a temporary transit site," said one aid worker showing journalists round the site on Friday.
Countries across the region have grown increasingly concerned about the huge numbers of Syrians crossing into their territories, taking up resources and straining local tensions.
But the Lebanese have particular reasons to worry, based on their long and troubled history with refugees and the especially explosive nature of their sectarian mix.
Thousands of Palestinians fled to Lebanon in 1948 and set up settlements. Many of those exiles fought in the 15-year Lebanese civil war and, in 2007, the Lebanese army fought militants based in a Palestinian camp.
The civil war deepened distrust between sects, and Shi'ite, Druze and Christians Lebanese fear that majority Sunni Muslim Syrians now coming in could disrupt the fragile demographic balance.
Any suggestion the Syrians might be staying only adds to those fears - some Lebanese officials blame refugees for a reported spike in crime.
"Our political system is sectarian which makes camps a cautious item when evaluating their viability," said Makram Malaeb, head of the Syrian crisis response for the Ministry of Social Affairs.
"There is also the issue of security - (camps are) areas that can have militants live in them."
Fighters supporting different factions in Syria's civil war have already clashed inside Lebanon. Officials fear Syrian rebels could turn refugees centres into fully fledged camps, pulling Lebanon into the conflict still further.
Until this camp was set up, Syrian refugees moved into unfinished buildings, the houses of friends or makeshift clusters of tents and shelters.
The new transit site glistens when compared to those more ad hoc settlements. The earth has been flattened, the tents are uniform, its inhabitants say they get running water and decent meals. Even the concrete toilets have toilet brushes.
"We still follow a 'no camp policy' but this is an exception," said Malaeb.
Refugees were expected to move on to other accommodation in Lebanon, such as empty or unfinished buildings within two weeks of arrival, he said.
But there was no "strict deadline," he added, and refugees spoken to by Reuters on Friday said they had no plan to leave.
Obeida al-Zahouri, 15, said he arrived with five members of his family two weeks ago after government jets started to bomb where they were living in the Syrian town of Yabroud.
"We don't know what we will do next. There are 70 families here in the camp and nobody has moved out," he said, wearing a thick leather jacket to keep out the cold.
The United Nations Refugee Agency has identified land and set aside money for 17 similar sites in Lebanon, said its representative in Lebanon, Ninette Kelley.
"It is not a question of UNHCR being prepared. It's a question of when the government gives the go ahead."
Officially-endorsed sites were necessary because "we reached a point here where the availability of shelter has outstripped demand," she added. (Editing by Andrew Heavens)