(Adds detail, total production)
By Julia Payne and Feras Bosalum
LONDON/BENGHAZI Aug 28 (Reuters) - Libya's Waha Oil Co. has resumed a small volume of Es Sider crude oil production, a senior Libyan oil official said on Thursday in the latest sign that output is improving despite unrest in the country.
The oil grade will be exported through the Es Sider port, the country's largest export terminal, which has reopened after being closed for a year due to protests and maintenance.
Libya's National Oil Corp has loaded two tankers of Es Sider this month after the resumption of exports from the neighbouring Ras Lanuf terminal which has a capacity around 220,000 bpd.
The Es Sider and Ras Lanuf terminals were the largest of the four ports that an eastern federalist group blocked for about a year, calling for a greater share of oil revenue.
Waha Oil Co, which pre-blockade exported around 320,000 barrels per day (bpd), is a joint venture between the Libyan National Oil Corporation and U.S. firms ConocoPhillips, Marathon Oil Corp and Hess Corp.
During the four-port blockade, the company sent small volumes of Es Sider crude to the port of Brega between November and August to be blended with the Brega grade for export and for the 120,000 bpd Zawiya refinery.
In the last three months, Es Sider output to Brega averaged around 3,000 bpd before being switched off for the Es Sider port, said Ibrahim al-Awami, general manager of inspections and measurement at the oil ministry.
On Thursday, a spokesman for Libya's National Oil Corp said total production had risen to 665,000 bpd, up from 650,000 bpd earlier this week but did not have a precise number for current Waha output.
Oil production in Libya has risen to more five times the level two months ago, in a rare success for the economy at a time when armed groups and two parliaments are fighting for control of the North African country.
Libya warned the U.N. Security Council on Wednesday the country could descend into full-scale civil war if heavily armed warring factions are not disarmed. (Writing by David Sheppard; Editing by Mark Potter and David Evans)