The Libyan militia leader accused of being part of the deadly 2012 attack on a US diplomatic compound in Benghazi, Libya, has been "compliant but not cooperative" with US interrogators, Representative Mike Rogers said.

Ahmed Abu Khatallah, captured in Libya earlier this month by US forces and held for nearly two weeks aboard a US Navy vessel, was transferred to federal custody on Saturday. He appeared in US District Court in Washington and, through a translator, pleaded not guilty to a terrorism charge in the attack that killed Christopher Stevens, the US ambassador to Libya, and three other Americans. Rogers, a Republican and chairman of the House Intelligence Committee, said Khatallah was being held in the Washington DC area after his arraignment.

"He's being held in, I would argue, an appropriately secure environment given the nature of his crimes against the US."