Rebel forces fought gunmen loyal to Muammar Gaddafi in eastern Libya on Sunday in the latest incident to undermine the insurgents grip in territory they hold.
The clashes renewed opposition fears that Gaddafis agents had infiltrated the area, days after the mysterious killing of the rebel military commander.
The assassination of General Abdel Fattah Younes, apparently by gunmen on his own side, has hurt the opposition just as it was winning broader international recognition and making gains against Gaddafis forces in the Western Mountains and elsewhere.
Rebel spokesman Mahmoud Shammam said clashes had broken out when rebel forces attacked a militia that had helped some 300 Gaddafi loyalists break out of jail near Benghazi on Friday. At least six rebels were killed in the fighting with the militia, whose members appeared to be experienced and armed with machineguns, rocket-propelled grenades and explosives.
Inside the barracks where they were holed up, rebels found more than 400 weapons, Libyas green flag and photos of Gaddafi.
"At 8 a.m., the barracks was brought under control. Thirty men surrendered and we took their weapons," Shammam told reporters. "We consider them members of the Fifth Column." The clashes reflect growing fears within the opposition that Gaddafi loyalists are exploiting the lawlessness that prevails in the east, which is awash with weapons and armed gangs, some secular or Islamist rebels, some vigilantes and some criminals.