CARACAS (Reuters) - Oil-rich Venezuela’s refinery network was operating at about a third of capacity, according to union sources and workers, as state oil company PDVSA [PDVSA.UL] struggles with equipment issues after years of underinvestment.

Venezuela’s biggest refinery, 645,000-barrel-per-day Amuay refinery, was operating at only 260,000 bpd with two of its five crude distillation units out of service, union leader Ivan Freites told Reuters, citing an internal report.

Its flexicoker remains down, Freites added.

A worker, who asked to remain anonymous because he is not authorized to speak to media, confirmed the situation.

Adjacent Cardon, with capacity of 310,000 bpd, was at 120,000 bpd, added Freites, a fierce critic of PDVSA and the government of socialist President Nicolas Maduro.

Meanwhile, the smaller refineries of El Palito and Puerto La Cruz, with capacities of 146,000 barrels per day and 187,000 bpd respectively, were barely refining any crude, according to a separate union leader and a worker.

The El Palito refinery was halted in October for scheduled maintenance, according to PDVSA. Union leader Freddy Alvarado said on Wednesday that the complex remained shut.

The catalytic cracking and alkylation units at Puerto la Cruz have been inoperative since the start of November, union leader Jose Bodas said earlier this month.

Over the weekend, the refinery’s reformer unit for octane 95 gasoline stopped operating, Bodas added on Wednesday. A worker at the refinery confirmed the issues.

PDVSA did not immediately respond to a request for information.

Venezuela’s refineries have been plagued with blackouts, equipment issues and stoppages for years.

PDVSA often blames problems on “saboteurs” intent on bringing down socialist rule in Venezuela, and says its foes and hostile media try to exaggerate refinery issues. Critics say years of underinvestment and poor maintenance are the cause.

U.S. refining firm Citgo Petroleum is sending more products to its parent company, PDVSA, to compensate for problems in the domestic network, according to sources and Reuters data.