BAGHDAD, April 29 (Reuters) - U.S. troops captured 72 suspected insurgents and seized nitric acid and other bomb-making materials in overnight raids on al Qaeda in the north and west of Baghdad, the U.S. military said on Sunday.

The synchronised operations took place in the provinces of Anbar and Salahaddin, both Sunni Arab strongholds.

In the city of Samarra alone, 36 people with links to al Qaeda in Iraq were arrested. In Karmah, near the insurgent bastion of Falluja, U.S. forces confiscated 20 drums of nitric acid and other bomb-making materials.

Insurgents have been shifting tactics and in recent months and have rigged nearly a dozen truck bombs with chlorine gas, mainly in western Anbar province.

The U.S. military commander in Iraq, General David Petraeus, has called al Qaeda "probably public enemy number one" in Iraq and said the Sunni Islamist group was bent on committing what he called "sensational" attacks designed to fuel sectarian violence.

AlertNet news is provided by