Aid agencies are warning that a planned U.S. troop surge in Afghanistan could lead to more civilian causalities.

In a report titled "Caught in the Conflict," 11 aid groups including Oxfam, ActionAid and CARE called on NATO to change the way it operates in Afghanistan.  

The Obama administration is sending an additional 21,000 troops and trainers to help fight a growing Taliban insurgency in Afghanistan. They will join a NATO-led force of more than 60,000 soldiers.

Oxfam official Matt Waldman told reporters in Kabul the deployment of more troops could lead to more fighting with civilians being caught up in the violence.  

Waldman also said military operations that cause civilian casualties create fear and resentment among Afghans, and erode support for the presence of international troops.

According to the United Nations, more than 2,000 civilians were killed last year in Afghanistan.  It said most deaths were caused by insurgent violence, but nearly 40 percent were attributed to U.S., NATO and Afghan military operations.

The report also raised concerns about some military forces who drive in white, unmarked vehicles normally used by humanitarian groups.  The report said that blurs the line between troops and aid workers, undermining their efforts to deliver assistance to vulnerable populations.  

Some information for this report was provided by AFP and Reuters.