An appeal for restraint issued yesterday by President George W. Bush reflects mounting concern that the US is being sucked into a gathering civil war in Iraq and will not be able to carry out planned troop reductions without leaving chaos, according to officials and analysts in Washington.

"I ask all Iraqis to exercise restraint in the wake of this tragedy, and to pursue justice in accordance with the laws and constitution of Iraq. Violence will only contribute to what the terrorists sought to achieve by this act," Mr Bush said after the bombing of the Shia Golden Mosque at Samarra and subsequent revenge attacks on Sunni mosques.