Afghan civilian deaths dropped 22 percent in the first six months of 2012 compared with a year ago, but the number of civilians killed in targeted assassinations surged, the United Nations said in a report released Wednesday.

The overall reduction was largely due to a decrease in the number killed by insurgents' homemade bombs and suicide attacks, the report said. The number of civilians who died in NATO attacks including airstrikes also fell.

It was the first time the U.N. data had shown such a sustained reduction in civilian deaths since it started counting in 2007. Even so, U.N. officials cautioned that fighting started to pick up in May and that civilian casualties are already spiking again.

"This report does not suggest that Afghans are necessarily safer or better protected in their communities, nor does it suggest any real or concerted attempt by anti-government elements to minimize civilian casualties," Nicholas Haysom, the deputy U.N.