A second bomb attack on one of Shia Islam’s most holy shrines in Iraq has raised fears of another surge in sectarian violence.

The attack, which destroyed the minarets of the Askariya shrine in the central Iraqi town of Samarra, was blamed on al-Qaeda and seen as an attempt to rekindle Sunni-Shia violence, which has declined in recent months. It threatened to dash hopes that a deployment of US forces could permanently interrupt the 15-month cycle of violence sparked by the first attack on the Askariya shrine in February 2006.