This comes after the slaying of ambassador Christopher Stevens in September in an armed assault on the US consulate in Benghazi.

Laurence Pope, 67, will officially serve as charge d’ affairs in the absence of an ambassador and could be there a year or more, State Department spokeswoman Victoria Nuland said.

Pope arrived late Wednesday in Tripoli. Nuland said no decision had been made about reopening the Benghazi consulate, after the buildings were heavily damaged and burned in the September 11 attack.

“Mr Pope’s selection as charge d’ affairs emphasizes the commitment of the United States to the relationship between our two countries and to the people of Libya as they move forward in their transition to a democratic government,” Nuland said.

She told reporters that Pope had “significant experience” in the region and described him a “very seasoned diplomat” whose expertise is needed “particularly in a complex time.”  Pope served in the US foreign service from 1969-2000.

He has served as a senior counterterrorism official at the State Department, as ambassador to Chad from 1993-96 and as political advisor to the commander of the US military’s Central Command, which covers much of the Middle East and Afghanistan.

Pope’s assignment follows tense hearings Thursday in the US House of Representatives, where opposition Republican legislators grilled State Department officials about failure to provide adequate security in Benghazi.

Republican presidential challenger Mitt Romney has been criticizing President Barack Obama’s handling of the Benghazi incident.