Workers at Libya's major Sharara field have restarted operations, two engineers working there said, after National Oil Corporation (NOC) announced a partial lifting of force majeure, Reuters reports.
They said flaring had restarted at the field and shared a video of it, and added that engineers had been returning to the area since Wednesday.
It was unclear when production might restart and there was no immediate comment from the NOC.
Two other NOC companies said they had issued directives to staff to start working to prepare to recommence production as soon as possible.
Libya's oil sector has stood almost entirely quiet since January, when eastern-based forces loyal to Khalifa Haftar imposed a blockade on energy exports during their ultimately foiled assault on Tripoli.
Haftar said on Friday the blockade would be lifted but NOC has demanded that his forces and allied mercenaries that it says pose a danger to its staff must leave all oil facilities.
On Saturday it lifted force majeure on what it described as "safe" fields and ports but not on any where fighters remain, though it did not name these. The NOC has said facilities were degraded during the shutdown and during years of conflict, which could slow any recovery.
Sharara has been plagued by security problems in recent years that have caused repeated full or partial shutdowns. The field is operated by the NOC in a joint venture with Spain's Repsol, France's Total, Austria's OMV and Norway's Equinor.
Elsewhere, Arabian Gulf Oil Co (AGOCO), an NOC company that had been producing around 300,000 barrels per day early last year, said it was ordering staff to start operations to prepare for a resumption in output as soon as possible.
Sirte Oil Co, another NOC company, said it had issued a directive to all staff to take the necessary measures to prepare for the start of production as soon as possible.