A bout of fighting in Libya’s capital has laid bare the fragility of an armed cartel that had brought a veneer of stability to the city and encouraged the gradual return of foreign diplomats and plans for elections in December.

Major battles have become rarer in Tripoli since last year as a handful of armed factions aligned with the internationally recognised Government of National Accord (GNA) consolidated their control.

But the ascent of four or five "super militias” has created resentment among groups excluded from the capital and from access to the spoils of Libya’s informal economy.

That has heightened the risk of conflict and made the challenge of disbanding militias or integrating them into regular security forces more complex, diplomats and analysts say.

Bringing armed groups to heel is seen as crucial to resolving a conflict that has divided Libya since a NATO-backed uprising forced Muammar Gaddafi from power seven years ago, slashing oil production and giving space to migrant smugglers and fighters.

Street battles on Monday and Tuesday pitted the Seventh Brigade, or Kaniyat, from Tarhouna, a town 65km southeast of Tripoli, against the Tripoli Revolutionaries’ Brigades (TRB) and the Nawasi, two of the capital’s largest factions.

The Kaniyat and other groups from outside Tripoli have noticed the success of rivals inside the city with growing unease. Reports about the wealth, power and extravagant lifestyles of some Tripoli rebel commanders have fuelled resentment.