Ansar al-Sharia is in control of the western entrance to the city, The (Toronto) Globe and Mail reported. The Canadian newspaper said Islamist militias carved up Benghazi in an unofficial agreement.
The group was thrown out of Benghazi after Stevens and three other U.S. citizens were killed five months ago in an attack on the U.S. consulate. The killings angered many Benghazi residents who rebelled against Ansar al-Sharia.
At the western gate, members of the group now inspect trucks, looking for hazardous materials and expired pharmaceuticals. There are Arabic signs saying "Ansar al-Sharia Patrol" and vehicles with its logo.
"I think we're doing very well," Rajab Alaghoury, a shift commander for the patrol, told The Globe and Mail. "We even sort out conflicts in the area. We are with the people."
Critics say the group is not just engaged in humanitarian activity.
"It's a sneaky way of infiltrating the government," said Fathi Baja, a political scientist who served on the country's transitional rebel council. "Nobody gave them permission. It's a tactic for returning to Benghazi. The government doesn't want a confrontation with them at this time."