Senior UN inspectors arrived in Syria today to investigate US allegations that Damascus was building a clandestine nuclear reactor for military purposes before an Israel air strike destroyed it in September.
Syria denies the accusations, saying the remote desert site housed an ordinary military building under construction.
Washington says the project at al-Kibar was camouflaged to hide its nature and Western nuclear analysts say satellite pictures taken since the September 6 bombing show it was bulldozed in a possible effort to remove incriminating evidence.
The International Atomic Energy Agency (IAEA) has indicated that uncovering the truth at this stage could be difficult.
The IAEA team in Damascus is led by Olli Heinonen, head of the Vienna-based UN nuclear watchdog's global inspectorate, and includes two nuclear technology experts familiar with Syria.
"We have our first meeting this afternoon. So we will start establishing the facts this evening," Heinonen told reporters at Vienna airport regarding the team's talks with Syrian officials.
They are due to have talks in Damascus and make a day trip to al-Kibar, the bombed site in northeastern Syria, before returning to Vienna on Wednesday.