A brigade leader tasked with transporting Younis from the front line near the oil town of Brega to the rebel capital of Benghazi confessed that his lieutenants killed Younis and two aides Thursday, the rebels’ oil and finance minister, Ali Tarhouni, said at a news conference Friday night.

Younis was to have appeared before a military committee investigating allegations that he had maintained ties with Libyan leader Moammar Gaddafi after defecting from the government to the rebel side in February.

Tarhouni said the assassins were members of the Abu Obaida Aljarah brigade, one of dozens of autonomous units that answer, more or less, to the central authority of the rebel council. The rebel government offered no motive for the killing.

The deaths have shaken the fractious Transitional National Council, which the United States recently recognized as the sole governing authority in Libya.

The rebel government has been challenged by bickering among political factions and tribes. The news that Younis was killed by his own side shows how stark those divisions are, and the violence will likely sow seeds of doubt among NATO officials and governments supporting the rebel side.

U.S. officials were struggling Friday to learn precisely what happened. The State Department’s emissaries to Benghazi sought explanations from the rebel leaders about the reasons for the slayings and how they would affect military operations going forward.

The deaths spurred questions about Western plans to turn over vast sums of money to the rebels. State Department spokesman Mark Toner told reporters that it was too early to second-guess the commitment to a unified and broad-based government.

“For us to make a judgment one way or the other about who’s at fault for this is just premature,” Toner said. “We’ve seen reports that this was an internal matter. We’ve reached no conclusions yet.”

Reports of gunfire were also reported in the opposition capital, heightening concerns in Washington that rebel factions were fighting among themselves. The shooting subsided later in the day.

NATO officials in Brussels said their warplanes bombed Libyan state TV satellite transmitters Saturday because they were being used to incite violence and threaten civilians. But Gaddafi’s TV channels continued to broadcast after the strikes.

With his dark sunglasses and confident style, Younis was popular with NATO officials and Middle East governments that support the Libyan opposition. But he was criticized as the rebels’ military advance in the east stalled, and was suspected of having conflicted loyalties after his decades of service to Gaddafi.

Mourners carried Younis’s coffin through Benghazi’s central square Friday and then to the cemetery. Local reporters at the scene said the crowds praised Younis as a martyr who died for the revolution — not a traitor to the rebel cause, as some charge.

According to an Associated Press reporter at the scene, Younis’s son, Ashraf, broke down and screamed, “We want Moammar to come back! We want the green flag back!” as his father’s body was lowered into the ground.

Warrick reported from Washington.