US commanders say a massive military operation targeting insurgents in Iraq will continue for several days. The offensive, involving 50 helicopters, is the biggest air assault in the country in three years. US Secretary of State Condeleeza Rice has praised the part played by Iraqi forces in the raid on Samara, north of Baghdad.Some 800 of the 1,500 troops involved are Iraqis. Washington’s top commander in the country said the operation was against al-Qaeda and Sunni insurgent groups. It is reported that 41 insurgents have been detained and a quantity of weapons found. The city is where the destruction of an important Shi’ite Muslim shrine last month sparked days of reprisals. Sunni Arab politicians have criticised the assault, saying it would send a discouraging signal at a time when Iraqi leaders are seeking a political solution to the country’s woes.