Geneva, July 31 (DPA) Afghan civilian deaths in the first six months of 2009 rose 24 percent, compared to the same period last year, the UN reported Friday, blaming air strikes and guerrilla warfare for many of the casualties.

'As the conflict intensifies and spreads, it is taking an increasingly heavy toll on civilians,' the UN said in a twice-annual review, noting that each year more unarmed people were being killed.

Armed opposition groups were responsible for 59 percent of the 1,013 civilian deaths, UN Mission in Afghanistan (UNAMA) data showed. Afghan security units and the international military forces were to blame for 30.5 percent. Some cases were unclear.

UNAMA said this was a rise in the percentage of deaths for which the militants were accountable.

A shift in tactics was also detected, as the insurgency switched from frontal or ambush attacks on international forces, to guerrilla type activities. These include so-called 'asymmetric attacks' such as suicide, car and road-side bombs, which are the main cause of civilian deaths in the conflict.

The militants were also 'basing themselves in civilian areas so as to deliberately blur the distinction between combatants and civilians', the report said.