Federal court has accused Ahmed Abu Khattala of involvement in assault that killed US ambassador and three other Americans

A former Libyan militia commander has denied charges filed in a US federal court accusing him of involvement in an attack that killed a US ambassador and three other Americans.

Ahmed Abu Khattala told the Associated Press he was not in hiding, nor had he been questioned by Libyan authorities over the September 2012 attack on the American consulate in Benghazi. That assault killed the US ambassador to Libya, Chris Stevens, and sparked Republican-led investigations in Congress over the attack and its aftermath.

Khattala has repeatedly denied any role in the attack.

"I am a Libyan citizen and the American government has nothing to do with me," he told an AP reporter by phone on Wednesday . "I am in my city, having a normal life and have no troubles, and if they have an inquiry to make, they should get in touch with Libyan authorities."

Officials in the US say he and an unspecified number of others are named in a sealed complaint filed in the US district court in Washington. It is unclear what charges they face. Libya's justice ministry declined to comment when asked about the charges.

Khattala was the commander of an Islamist militia group called Abu Obaida Ibn Jarrah. A Libyan witness interviewed after the attack has placed him at the compound directing fighters. But Khattala insists he had abandoned the militia and begun working as a construction contractor.