UPDATE 2-ANALYSIS-Libya's tribal politics key to Gaddafi's fate
"In Libya, it will be the tribal system that will hold the balance of power rather than the military," said Alia Brahimi, head of the North Africa programme at the London School of Economics.
"I think you will see defections of some of the main tribes if that is not happening already. It looks like he has already lost control of the east of the country where he was never popular and never fully managed to consolidate his power."
Eastern Libya is the site of much of its oil reserves. On Tuesday, a Reuters correspondent reported that Gaddafi's forces appeared to have abandoned their positions on the border with Egypt which were now in the hands of men armed with clubs and Kalashnikovs who said they were opposed to his rule.
Who, if anyone, those men were answering to was not immediately clear. While herder and tribal lifestyles have declined in Libya in the face of rising oil-fuelled urbanisation, traditional power structures are said to remain strong beneath the surface.
In Egypt and Tunisia, the armies proved to be the supreme political force, easing unpopular leaders Hosni Mubarak and Zine al-Abidine Ben Ali from office in part because they were reluctant to fire on protesters. But Libya is very different.
Long largely closed to outsiders, details of its complex mix of alliances and loyalties are scarce. Experts generally agree part of Gaddafi's strategy for retaining power has been to keep his own tribe in important positions.
Some analysts say key members of his family have their own military formations, again usually members of their own Gaddadfa tribe. Once largely nomadic herders, the Gaddadfa were sidelined by Libya's former monarchy but allowed to join the armed forces and police, then considered secondary organisations. Continued...