Libya’s National Oil Corporation (NOC) has informed its customers that it cannot guarantee crude oil deliveries for September as it faces protests and strikes at its oil fields and export terminals,

Shipments will be “modified”, rather than cancelled, according to NOC chairman, Nuri Burruien, Reuters news agency reports.

Libyan oil output has dropped to below 500,000 barrels a day (b/d) from highs of 1.3 million b/d earlier in the year. The Ras Lanuf and El-Sider oil export terminals, which have a combined capacity to export 600,000 b/d, have faced repeated closure due to strikes by staff, preventing loading. Reuters reports that as many as 15 crude oil tankers are waiting outside the two ports to be loaded.

The El-Sider terminal is operated by the Waha Oil Company, a joint venture of NOC and three US oil firms, Marathon, Hess and ConocoPhillips. Ras Lanuf port is operated by Harouge Oil Operations, a joint venture of NOC and Canada’s Suncor.