* Output at 1.3 mln bpd from near pre-war levels of 1.6 mln
* Protesters in east calling for boycott of Saturday's poll (Adds deputy oil minister quote, background)
By Marie-Louise Gumuchian and Ali Shuaib
TRIPOLI, July 6 (Reuters) - Libyan oil output has been reduced by around 300,000 barrels per day (bpd) as protests by groups demanding greater autonomy for eastern Libya a day before national elections have blocked operations at some oil terminals, officials sai d on Friday.
The protests, combined with other storage and market-related factors, have pushed output down to a round 1.3 million bpd from the level of nearly 1.6 million bpd to which production has steadily climbed since the end of last year's war ousted Muammar Gaddafi.
"You are talking about a shortage in daily production of about 300,000, plus or minus," NOC Chairman Nuri Berruien told Reuters by telephone.
"Most of the cut is because of the unrest."
Berruien said political protesters had prevented the lifting of crude from terminals in the east, such as Al-Sidra and around Ras Lanuf and cited storage and market factors as reasons for the cut.
"(The) unrest has nothing to do with the oil sector," he said. "Some people are stopping the lifting of crude... And accordingly the companies have to reduce their production because some of the tanks are full."
Berruien said the disruption by protesters had begun on Thursday evening. He said some of his staff had been told the disruption would last 48 hours.
"For the security of the people working there and the equipment, it was decided to minimise the exportations from the host terminals, Sidra and Ras Lanuf, and in this case you have to reduce the production," Deputy Oil Minister Omar Shakmak told Reuters. He said output was on average at 1.35 million bpd.
Berruien would not be drawn on who the protesters were.
A self-proclaimed autonomous council for the oil-rich province has called on people in the region to boycott the July 7 election for a national assembly, saying it will not give adequate representation to the east.
The anti-election group also now includes some tribes as well as disgruntled former rebel forces gathering at Wadi Ahmar, which lies west of Benghazi, analysts have said.
Libya's east, home to most of the country's oil, was starved of cash during Gaddafi's 42-year rule, and calls for federal rule have been fuelled by long-standing complaints it has been deprived of its fair share of wealth.
Saturday's election for the assembly, which will name a new prime minister, help draft a constitution and enact legislation is a crucial milestone in shaping Libya's institutions. (Editing by James Jukwey)