A top rights advocate in Congress demanded Secretary of State Hillary Clinton cut off aid to Tunisia on Tuesday because it refuses to allow US officials to interrogate a suspect in the Benghazi attack.
Republican congressman Frank Wolf accused Tunis of barring FBI officials from interviewing Ali Harzi, who he said was detained trying to enter Turkey after the deadly September 11 attack on the US mission in Benghazi, Libya and eventually deported back to his home country.
A Federal Bureau of Investigation interrogation team "waited on the ground in Tunisia for five weeks" before departing earlier this month after "continued obstruction," according to Wolf.
"These unnecessary and unfounded delays are inexcusable and demonstrate that Tunisia is no friend or ally of the United States," he wrote in a letter to Clinton.
"How is it possible that Tunisia is receiving more than $300 million in taxpayer dollars while simultaneously obstructing FBI efforts to investigate the death of four Americans?"
US ambassador Christopher Stevens and three other Americans died in the assault on the US mission in Benghazi, and Republicans have seized on President Barack Obama's administration's shifting narrative of what happened.
US officials originally said the assault stemmed from a "spontaneous" reaction to an anti-Muslim video made on US soil.
The administration subsequently revised its position to say the attack was carried out by militants linked to Al-Qaeda. State Department and FBI probes are currently under way.
Wolf said cutting off funds would send a "strong signal" to Tunisia that they will not benefit from US aid until they grant the FBI access to Harzi.
Last month Tunisia's justice ministry identified the similarly named Ali Hamzi as a Benghazi attack suspect detained in Turkey and deported back to Tunisia, and said he had been charged with belonging to "a terrorist group based abroad."
Should Clinton fail to halt the aid, Wolf said he would initiate legislative procedures to block the funding.
Clinton had planned to visit Morocco, Tunisia and the United Arab Emirates early this week but cancelled the trip due to illness, her office said.