The U.N. Assistance Mission in Afghanistan said 2011 marked the fifth consecutive year in which civilian casualties increased as a result of armed conflict. The mission said civilian casualties continued at an unacceptable rate despite improvements since the beginning of the year.
Afghan forces are expected to take control over security operations by 2014. UNAMA said about 75 percent of the country will be under Afghan responsibility within the next six months.
"To the Afghan people, the credibility and success of transition of security to Afghan forces will be measured by reduced civilian casualties and real improvements in security, particularly in conflict-affected areas," Jan Kubis, U.N. special envoy to Afghanistan, said in a statement.
"Only through increased actions to protect civilians will deaths and injuries to Afghan women, children and men from the conflict be radically reduced during transition."
UNAMA said 31 percent of civilian casualties in the country were the result of improvised explosive devices planted by anti-government forces.
The Taliban in early May announced the start of their spring offensive, saying it was the Islamic duty of Afghans to take up arms against "foreign occupiers."