KIRKUK, Iraq, May 16 (UPI) -- More than 300 members of the Sunni paramilitary force Sons of Iraq boosted the ranks of the local police following graduation from the Kirkuk Police Academy.

The graduates come from the local Sons of Iraq unit operating in Hawijah about 60 miles south of Kirkuk. The U.S. military said in a briefing on the graduation the area was once considered one of the more violent areas in northern Iraq, witnessing an average of 10 insurgent attacks per day.

The Sons of Iraq contributed to a substantial drop in the level of violence since December, however, and U.S. military officials say they will bolster the ranks of the local police force with their security experience.

In related news, a joint Iraqi-U.S. military operation in Maderiyah just south of Baghdad uncovered several weapons caches.

The U.S. military said most of the weapons uncovered were in a condition suggesting they were placed recently in the area.

The caches consisted of over 300 anti-personnel grenades, anti-aircraft rockets and a 23 mm anti-aircraft gun mounted on a tripod. An additional cache consisted of several large-caliber ammunition rounds and an SS-30 rocket that has a six-mile range.