A video posted online in the name of a shadowy militant group is claiming responsibility for twin suicide bombings in the Syrian capital this week that killed 55 people.

In the video posted late Friday, a group calling itself the Al-Nusra Front says the bombing was in response to attacks on residential areas by the regime of President Bashar Assad.

"We fulfilled our promise to respond with strikes with explosions," a distorted voice says.

The video's authenticity could not be independently verified. The Al-Nusra Front has claimed past bombings in Syria through posts on militant websites. Little is known about the group.

Thursday's bombing in Damascus raised fears that al-Qaida-linked extremists are joining the anti-Assad fight.

THIS IS A BREAKING NEWS UPDATE. Check back soon for further information. AP's earlier story is below.

DAMASCUS, Syria (AP) — The latest suicide bombings in