(Reuters) - Libyan rebels clashed in the early hours of Sunday with an armed gang they said was loyal to Muammar Gaddafi, the latest sign of growing lawlessness in the rebel-held east.
Rebel spokesman Mahmoud Shammam told reporters in the opposition capital of Benghazi that the clashes broke out when rebel forces attacked a militia that had helped some 300 Gaddafi loyalists break out of jail Friday.
Rebel forces surrounded the barracks in which the militia, which calls itself the Nida Brigade, had been holed up.
At least six rebels were killed in the clashes, he said, which involved rocket-propelled grenades and machine guns.
"At 8 am, the barracks was brought under control. Thirty men surrendered and we took their weapons," Shammam said.
"We consider them members of the fifth column," he added, reflecting growing fears among the opposition that Gaddafi loyalists have infiltrated their ranks.
The 300 Gaddafi soldiers and loyalists who broke out of jail were apparently still at large.
The clashes broke out three days after rebel military commander Abdel Fattah Younes was killed, apparently by gunmen fighting on the rebel side against Gaddafi's 41-year rule.
Speculation has swirled in Benghazi over who killed Younes, who was part of Gaddafi's inner circle since 1969 and was Libya's interior minister before he defected in February.
Some Libyans suspect his execution was ordered by rebel leaders for treason, many say he was killed by Gaddafi spies, and others suggest a rebel splinter group had acted alone.
Whatever the truth, the infighting among militias in Libya's east deepens concerns among the rebels' Western backers, keen to see them prevail in a five-month-old civil war but frustrated by their lack of unity and worried over Islamist influence.
In a news conference announcing Younes' death, rebel leader Mustafa Abdel Jalil called on all armed groups to come under the umbrella of the Transitional National Council, lay down their arms or face justice.
(Reporting by Rania El Gamal, Writing by Lin Noueihed; Editing by Angus MacSwan)