The military wing of Hamas, a former ally of President Assad, is training the rebel Free Syrian Army in eastern Damascus. Diplomatic sources said that members of the Ezzedine al-Qassam Brigades were training FSA units in the rebel-held neighbourhoods of Yalda, Jaramana and Babbila.

The development appears to confirm that Hamas, the Palestinian militant group that runs the Gaza Strip, has made a final break with its former Syrian host and fully embraced the patronage of Qatar, the small but influential Gulf state that is a major financial and logistical backer of some rebel factions.

“The Qassam Brigades have been training units very close to Damascus. These are specialists. They are really good,” said a Western diplomat with high-level contacts in the Assad regime and