The Daesh group is in a place now enabling it to target Damascus, after it seized Syria's last border crossing with Iraq on Friday, The Financial Times reported.

The paper said such fairs emerged following a slew of advances in in Syria and Iraq that have cast doubt on the effectiveness of the international coalition battling the jihadists.

The border capture caps off a week of spectacular gains for Daesh, which seized Syria's ancient city of Palmyra and the Iraqi provincial capital of Ramadi, an hour's drive from Baghdad.

Palmyra, site of a UNESCO World heritage site, gives the group access to nearby military bases and gasfields as well as highways leading to Damascus, the capital, and the central city of Homs.

There are fears that Daesh will now target the countryside ringing Damascus, Assad's seat of power. Known as the "Ghouta", the rebel-held area has been under a regime blockade for nearly two years. Activists in Damascus and its environs have long worried about the potential for Isis sleeper cells within rebel ranks demoralized by the opposition’s inability to end the siege.