The Syrian Government's former spokesman, Jihad Makdissi, is co-operating with US intelligence officials, who had helped him flee to Washington almost one month ago.
Makdissi became one of the most prominent regime defectors in late November when he left Beirut after first crossing from Syria.
The Guardian had reported at the time that he had fled for the US, possibly in return for asylum, which has now been confirmed.
According to the report, Syrian officials have denied that Makdissi has defected, saying he had instead taken three months of administrative leave.
However, at the time of his departure, Hezbollah's television network in Beirut, not known to be out of step with the regime line, announced that the spokesman's views had strayed from official positions and that he had been fired, the report said.
The state department did not respond immediately to requests for comment, and the CIA was unwilling to discuss the story.
Makdissi is the most senior member of the regime to defect since Syrian Prime Minister Riyad Hijab fled with his family to Jordan in August, the report said.
According to the report, Makdissi, a former senior diplomat at the Syrian embassy in London, worked closely with foreign minister, Walid al-Mouallem and information minister, Adnan Mahmoud, whom he dealt with regularly as security steadily decayed over the past 18 months.
Details of Makdissi's journey to the US are not yet known, although Britain has previously denied that he arrived in the UK after fleeing Beirut, the report added. (ANI)