WASHINGTON: The Obama administration is declaring a Syrian rebel group with alleged ties to al-Qaida as a terrorist organisation. It is an effort to blunt the influence of extremists as the US steps up cooperation with the Syrian opposition.    

The State Department's action blocks Jabhat al-Nusra's assets in the US and bars Americans from doing business with the group.

The move hasn't been announced officially but was included in the Federal Register on Monday. The department said the group was part of al-Qaida in Iraq.

Jabhat al-Nusra has claimed responsibility for suicide bombings on Syrian government targets, raising fears of growing Islamic extremism among the opposition.

Secretary of State Hillary Rodham Clinton is traveling to North Africa this week to try to bolster moderates hoping to end Syrian President Bashar Assad's regime.