MARJAH, Afghanistan - U.S. Marines and Afghan soldiers advanced through poppy fields of Marjah on Saturday under withering gunfire from Taliban fighters shooting from mudbrick homes and compounds where families huddled in terror.

President Hamid Karzai urged NATO to do more to protect civilians during combat operations to secure Marjah, a southern Taliban stronghold and scene of the biggest allied ground assault of the eight-year war.

NATO forces have repeatedly said they want to prevent civilian casualties but acknowledged that it is not always possible. On Saturday, the alliance said its troops killed another civilian in the Marjah area, bringing the civilian death toll from the operation to at least 16.

Addressing the opening session of the Afghan parliament in Kabul, Karzai held up a picture of an 8-year-old girl who lost 12 relatives in a NATO rocket attack during the second day of the Marjah assault, which began Feb. 13.

Karzai said NATO had made progress in reducing civilian casualties and thanked the top commander, Gen. Stanley McChrystal, for "standing with us honestly in this effort." But Karzai said more needed to be done to protect civilians caught up in the fighting.

"We need to reach the point where there are no civilian casualties," Karzai said. "Our effort and our criticism will continue until we reach that goal."

The Marjah operation is a major test of a new NATO strategy that stresses protecting civilians over routing insurgents as quickly as possible. It's also the first major ground operation since President Barack Obama ordered 30,000 reinforcements to Afghanistan to curb the rise of the Taliban.