OPEC oil producer Libya told its customers on Tuesday it could make no promises on crude deliveries next month as on-off strikes paralysed its major sea terminals, Reuters reported. The North African country's exports provided nearly 1.5 percent of global supplies until June, but output has since plunged, putting upward pressure on international oil prices. Libya's state National Oil Corp (NOC) said in a statement it could provide no September loading schedules, normally sent to contract buyers of its gasoline-rich crude by this time of the month. The NOC chairman, Nuri Berruien, told Reuters the September schedules "will be modified, not cancelled...because of the current sit-ins at ports and fields." Labour unrest gripping Libya's oilfields and ports has cut output to the lowest since the 2011 war that overthrew Muammar Gaddafi, and some analysts say it is well below 500,000 barrels per day (bpd), compared with 1.3 million bpd in June. Some estimates put exports as low as 300,000 bpd, depriving the 90 million bpd world market of approaching 1 million bpd - largely consisting of highly-prized light sweet crude. Striking security guards on Monday again shut the country's two biggest crude export terminals, Ras Lanuf and Es Sider, just hours after they had reopened from a two-week stoppage. Late on Monday the deputy oil minister said exports from Es Sider could resume on Thursday, once some output from associated oilfields restarted and a new schedule was made, but the NOC statement admitted firm undertakings for September were not yet possible. -- SPA 19:00 LOCAL TIME 16:00 GMT تغريد