By Anthony Deutsch and Fredrik Dahl
THE HAGUE, April 12 (Reuters) - A team of U.N.-led experts is on standby in Cyprus waiting for the go-ahead to investigate allegations of chemical weapons attacks in Syria, but the mission has been held up by diplomatic wrangling over their powers and how to keep them safe.
The team of at least 15 investigators includes analytical chemists, able to collect and test suspected samples, and World Health Organisation experts on the medical effects of exposure to toxins, who could examine alleged victims.
For now, the deployment is at an impasse.
Syria has asked for the team to investigate what it says was a poison attack by rebels in the northern city of Aleppo last month. But Damascus has rejected demands by the opposition that the inspectors also be sent to investigate other locations where rebels say government forces used chemical munitions.
U.N. Secretary General Ban Ki-moon says the mission can only be successful if it considers allegations from all sides. U.N. Security Council members have split on the issue, with Russia backing the Syrian government position and the United States, Britain and France backing the opposition.
The mission will test the diplomatic skills of its leader, Swedish scientist Ake Sellstrom, who helped dismantle Iraq's biological and chemical weapons programme in the 1990s.
"He's competent and honest, which is very important," Sellstrom's former boss in Iraq, Rolf Ekeus, told Reuters. "He's also not a politician or a diplomat, but a scientist. He has experience in Iraq in tough times, so he knows how to face uphill battles."
But deploying inspectors to the frontlines of a sectarian war would be unprecedented, and, says one veteran arms inspector, risky to the point of being foolhardy.
"Any Western person volunteering for such a team should see it as a suicide mission. The ground is just too unstable," Robert Kelley, an American who headed an International Atomic Energy Agency inspection team in Iraq, told Reuters.
"I would certainly not volunteer for this mission on the basis of such weak hearsay," he said, adding: "There is little chance of technical success and they can be used by propagandists of any side for any reason."
Sellstrom's team is not mandated to determine who is to blame for possible attacks, only to establish scientifically whether chemical weapons have been used in the two-year-old conflict that has claimed an estimated 70,000 lives.
The Hague-based Organisation for the Prohibition of Chemical Weapons (OPCW) is providing scientists and equipment. The team will consist of experts mostly from Nordic countries, Latin America or Asia. None will be from a permanent U.N. Security Council member, to avoid an appearance of bias.
Western countries say they believe Syria has chemical weapons stockpiles, and their use would be a "red line" that could justify foreign military intervention. Syria has not publicly confirmed whether it possess chemical arms but says it would never use them in an internal conflict.
Damascus also says it is worried the inspectors could end up playing the role they played in neighbouring Iraq, where their suspicions that then-leader Saddam Hussein was hiding banned weapons were used by Washington to justify the 2003 invasion.
If they are deployed, inspectors armed with hand-held chemical agent detectors would head to alleged sites of use. The area would be sealed off like a crime scene while video and photographic evidence was recorded.
Soil, air, water and possibly blood and urine samples from alleged victims or dead animals could be examined at a basic mobile laboratory before being split, sealed and sent to the OPCW's headquarters in The Hague and two other labs.
Syria has said it wants to be provided with its own samples so that it can check the inspectors' work.
Officials in the town of Douma near Damascus - one of the areas that the government wants to keep off limits - said they have preserved the bodies of six alleged victims of chemical munitions in a morgue.
A letter to Sellstrom, sent on behalf of local town leaders by a leading opposition figure, said the deaths occurred in the villages of Adra and Otaiba. A further 32 people have symptoms of illness and have offered to be examined, it said.
Syria is one of eight countries - including its neighbours Israel and Egypt - that have not joined the 1997 Chemical Weapons Convention, which means it has no obligation to cooperate with OPCW experts.
"With the government resisting access, it is a tricky situation for Sellstrom. I would seek a broader mandate from the U.N. But first they should start with one investigation and then go from there. If not, they will not go at all," said Ekeus.
Hans Blix, Ekeus's successor as head of the inspection team that operated in Iraq before the U.S. invasion, said Syria poses tougher challenges than Iraq, because of the lack of international leverage over both the government and the rebels - to say nothing of the added risk of operating in a war zone.
He said the mission should not launch without permission to look at allegations from both sides.
"I don't think the U.N. could really content itself with taking a look at (only) that which the government alleges was made by the rebels. They have to be even-handed," he said.
While politics are now the main barrier, logistics and security are also important issues that need to be worked out. Among unresolved problems: how to keep the inspectors safe when crossing between government and insurgent-held areas.
Ekeus said that would make it harder to do the job than in pre-invasion Iraq.
"I could demand access anywhere, anytime with the U.N. mandate. But Sellstrom will have to say 'I want to go there' and they can simply say 'we can't give you security' And it's over." (Additional reporting by Stephanie Nebehay in Geneva, Fredrik Dahl in Vienna, Oilver Holmes in Beirut and Louis Charbonneau in New York; Editing by Peter Graff)