The largest oil field in Libya has been shutdown since 19 July, according to a statement released by the country’s National Oil Corporation (NOC).

The El-Sharara field was producing 290,000 barrels a day (b/d) before the shutdown.

A suspected valve closure has been blamed for the shutdown and the NOC says an investigation has been launched to find out more information about the closure of the field.

Over recent years, it has become common for militias with grievances or demands to shut down oil infrastructure as a way of gaining political leverage.

The NOC said it was not immediately clear what had caused the shutting of the valve in this instance.

The NOC said that the incident occurred in Hamada, an area of desert in western Libya, surrounded by a number of towns and cities.

The closure of El-Sharara is expected to reduce Libya’s production to just over 1 million b/d.

Earlier this month, before the field was closed, NOC chief Mustafa Sanalla said Libya was producing a total of 1.2-1.3 million b/d.

Libya’s NOC operates the El-Sharara field in partnership with Spain’s Repsol, France’s Total, Austria’s OMV and Norway’s Equinor.