With oil export revenues drying up and petrol imports threatened, Libya's government begins to contemplate cuts to state spending as it faces stark choices in ending the disruption.

As of early September, virtually all of Libya's oil export capacity has been shut down by armed protesters or labour unrest.

According to information available at the time of writing, ports at Es Sider, Ras Lanuf, Zueitina, Hariqa and Zawiya all appear to be non-operational. The only functioning export points are at Brega - which reopened last weekend - and at the offshore platforms at Bouri and Al Jurf.

Other major oil fields around the country have been forced to halt production while refineries have run out of crude supply, raising the spectre of fuel oil or gasoline stocks being depleted.

Production is now likely to have fallen well below the 250,000 barrels per day (bpd) which Prime Minister Ali Zeidan said was being pumped last week.

A pipeline connecting the Zawiya terminal and refinery, in western Libya, was also attacked last week by an unknown group, forcing the major south-west El Feel and Sharara fields to shut down.

The Zawiya disruption and ongoing closures at the Ras Lanuf refinery, Libya's largest, raises the prospect of petrol shortages. Drivers in Tripoli queued in long lines last week in a fresh round of panic-buying, which prompted the National Oil Corporation (NOC) to issue a statement saying that stocks were adequate and supply chains were operational.

The energy commitee of the General National Congress (GNC), which met on 2 September to discuss the impact of the closures, published a statement saying that the port closures had also led to the "suspension" of petrol imports, which provide around 70-75% of domestic consumption needs.

It also said that a lack of fuel supply had caused damage to power plants in eastern and western regions, had delayed development projects and caused a loss of reputation for Libya's ability to fulfill its oil export contracts.

Separately, sources from the Arabian Gulf Oil Company (AGOCO), quoted in state news agency LANA on 2 September, said that tankers moored off the Hariqa terminal in Tobruq were costing Libya around $11,000 (LD14,000) per hour, and had been waiting to load for some two weeks.

Losses to state finances so far totalled $3bn (LD3.8bn), according to the GNC statement, and would result in a "large fiscal deficit" this year, claiming that the government would be unable to pay for "food, medicine, electricity and public-sector salaries" from the beginning of 2014.

Late last week an expanded cabinet meeting, involving Zeidan and a number of senior ministers, discussed the impact of the unrest on this year's state budget.

Deputy Central Bank governor Ali Habri recently reported that Libya earned some LD30.7bn ($24bn) in crude revenues during the first seven months of 2013, with income above budgeted projections thanks to high global oil prices.

But the disruption from mid-July onwards is likely to have dried up state finances to a trickle since then.

Government budgets in Libya are now more reliant on crude exports than they were prior to 2011, partly thanks to lower tax and duties revenues, with oil providing 95% of income in 2012 compared to 90% in 2010.

Although the government sits on sizable foreign reserves, and assets held overseas, its domestic spending commitments are so huge - and are so vital for ensuring social stability through food subsidies and public-sector salaries - that room for maneovure is limited.

Resolving the port closures is made more complex by the fact that their causes appear to differ from place to place, though at the heart of the disruption in the east appears to be the role of former members of the Petroleum Facilities Guard (PFG) and demands for a federalist political structure in Libya. 

The PFG was set up after the 2011 revolution in a bid to incorporate rebel fighters involved in protecting oil and gas facilities during the conflict, but has since been involved in disputes with central government.

Over the summer, security guards at several fields and terminals have either gone on strike or staged sit-ins to demand bigger salaries, better conditions or more government investment in their local areas.

In mid-August Ibrahim al-Jathran, the former head of the eastern division of the PFG, was reported to have set up a political council in Ras Lanuf - home to a major refinery and petrochemicals complex - to spearhead demands for greater devolution of power.

Federalist groups in eastern Libya, home to the majority of its oil export and production capacity, want greater control over how crude revenues are spent and allocated. 

Since taking over oil ports in late July, the groups have attempted to sell crude oil independently of the National Oil Corporation (NOC), with reports that tankers had tried to dock at Ras Lanuf and Es Sider to load illicit shipments.

Zeidan has repeatedly threatened to use force to bring the terminals back under Tripoli's control, and bomb tankers that tried to enter ports without NOC permission, but has so far avoided a major confrontation.

However government control over large parts of the country remains weak or even non-existent, with large volumes of arms still in the hands of independent groups and its own police and armed forces still in their infancy.

With time and financial reserves starting to run out, it now effectively faces a bleak choice between a negotiated agreement and acceding to the various groups' demands, or deploying what military power it does wield in a bid to wrest back control of the ports, and in the process risking an escalation of violence.