* Senior ICRC official cites complex negotiations with factions
* U.N.'s WFP says growing insecurity in Syria hits operations
By Stephanie Nebehay
GENEVA, Sept 20 Aid workers are having to negotiate with an increasing number of rebel sub-factions to organise delivery of aid to Syrian civilians, while the government continues to deny access to many areas, severely hampering their work, agencies said on Friday.
Bringing supplies from the capital to the divided northern city of Aleppo - a distance of 355 kms - is slow and fraught, said Pierre Kraehenbuehl, director of International Committee of the Red Cross (ICRC) operations worldwide.
"When colleagues of ours travel from Damascus to Aleppo it is something between 50 and 60 checkpoints on the way. This is what you have to deal with," he told a news conference in Geneva.
"Therefore it multiplies the number of people that you need to talk to on the ground, from a variety of groups, everything from organised armed forces across to loosely structured non-state groups, rebel groups, but also of course the criminal actors," he said.
"... there is very strong fragmentation on the opposition side and you have multiplicity of groups, sometimes even disagreement within the same group, so that you have to negotiate with several factions within the same opposition group."
The World Food Programme, which is trying to bring rations to three million Syrians a month, said armed groups in the northeast have blocked roads and more areas of Damascus and the countryside around the city are inaccessible due to fighting.
Hundreds of rebels have pledged allegiance to al Qaeda-affiliated forces in northern and eastern Syria, activists and Islamist sources said on Friday, strengthening the group's control in the region.
Entire units have joined the small but powerful al Qaeda-linked groups - the Nusra Front and the Islamic State of Iraq and the Levant (ISIL) - in recent days, according to the sources inside Syria.
The ICRC, an independent humanitarian agency, is in contact with all groups and is able to work in some opposition- and government-held areas of Aleppo, Kraehenbuehl said.
"There is no doubt whether in the north or other regions of the country where the opposition groups are strongly present it is the multiplicity of groups that makes the dialogue challenging," he said.
"Because to understand who is who, who to talk to, who can provide you guarantees that when your convoy goes through a given region that it is respected, this is the challenge."
The government of President Bashar al-Assad has had "a rather constraining and limiting attitude" toward aid workers, since the fighting began in early 2011, Kraehenbuehl said.
Syrian officials, invoking security concerns, this month again refused a greenlight for access the old city of Homs, where several thousand people are believed to have been stranded for months, he said.
"The issue of our access to Homs old city is currently unresolved, despite agreements that we had been able to negotiate this time locally with all actors, there was a central red light that was given," he said. "It's not the only place."
WFP has recorded nearly 50 incidents of theft of supplies or confiscation of food trucks by armed groups this year, said the U.N. agency's spokeswoman Elisabeth Byrs.
A WFP warehouse in the countryside outside Damascus caught fire this week after being hit by three mortar bombs, she said.
"We call upon all parties of the conflict to allow the safe passage of food to the families that live month to month on WFP's food rations," Byrs told a news briefing.