TOBRUK, Libya (Reuters) - If anyone understands the deep divisions over how to resolve the blockade of Libya's eastern Hariga oil port, it is the family of local mayor Faraj Yassin.
Protesters shuttered the 110,000-barrel-per-day port last summer to pressure a government struggling to impose order three years after Muammar Gaddafi's demise.
The dispute is one of many involving oil facilities of the OPEC country that have contributed to a cut in petroleum output to 230,000 bpd from 1.4 million bpd in July. Three other ports in the east have also stopped exporting.
For Yassin, the shutdown brings trouble, cutting off vital state revenues and eroding the budget just when the government needs all the help it can get in Libya's stuttering transition to democracy.
But for his brother-in-law, Mansour al-Salhin, the protest is a justified battle against a central government that he feels has taken oil revenues at the expense of his hometown Tobruk and Libya's east.
The Hariga conflict highlights the chaos in the North African oil producer since the fall of Gaddafi, and the complications for its fragile government in overcoming protests holding its vital oil industry hostage.
Already battling to end separate protests at three key eastern ports nearby, Libya's government has been trying to negotiate a deal to overcome the blockade at Hariga and revive falling oil revenues vital for public spending.
But talks have collapsed after the protest camp fractured into rival groups with different demands. The question of whether oil should flow or not is dividing families, protest leaders and oil workers in the city near the Egyptian border.
Tobruk is dominated by tribes vying over a bigger slice of the vast oil wealth and regional power.
Town council head Yassin agrees with the demands for more regional authority and development, but opposes pressuring for those rights by halting oil exports.
"We are not happy that the port is closed," he said, sitting in his office in a luxury hotel near the port. "This has a negative impact on all Libyans."
Yassin has been trying to negotiate an end of the protest and even went with Prime Minister Ali Zeidan live on television in October to announce Hariga would resume its work.
But his deal was killed by tribesmen who sidelined a moderate leader to team up with former militia leader Ibrahim Jathran, who have seized the three other eastern ports.
Jathran wants a greater oil share and more local autonomy, difficult demands to deliver for a weak government. But his Tobruk ally is tougher, demanding an end to the government and the interim parliament, known as the General National Congress.
"We want the government and General National Congress to go," said Salhin, a protest leader.
Some locals dismiss him as unpopular, but Salhin, who is married to Yassin's sister, draws support from his dominant Al-Abidat tribe. He walks around with his son, dressed in military uniform, as bodyguard.
"Seventy percent of the oil comes from the east. We want our share for Cyrenaica," said Salhin, referring to the historical name of Libya's east. "I want our rights for Cyrenaica."
When asked whether talks with Tripoli might succeed he said: "The government has not responded to our demands."
Jathran's troops in the other eastern ports -- Zueitina, Es Sider and Ras Lanuf -- have also been in indirect negotiations with Zeidan's government to end their protest. Their self-appointed eastern region prime minister said earlier this year a deal was close, but there is no sign of one yet.
Zeidan has repeatedly warned he may use force to end those blockades, which are cutting off 600,000 bpd of oil export capacity. But with no real army at his command, his government is unlikely for the moment to deliver on those threats.
Jathran -- a former oil facilities guard commander -- defected with thousands of his troops to take over the three ports now under his control. But he has been unable to deliver on threats he will sell oil independently of Tripoli.
At Hariga, though, the military strength of the protesters is less clear. But it does not take much to threaten international oil tankers approaching Hariga.
Unlike the other seized eastern ports where former oil guards block gates there are no armed protesters at Hariga. Oil workers still go to work though there is little to do.
The two export jetties, now inhabited by cormorants, are located at the end of a natural bay -- any docking tanker could be easily shot at by trucks mounted with anti-aircraft guns from the opposite coast. Such gun trucks are commonly used by militia brigades in lawless parts of Libya.
"There is no tanker going from here," Rajab Abdelrasol, the terminal manager. "We cannot do anything with this political problem."
Local military commanders dismiss Zeidan's threats to clear blocked ports by force, even if they themselves oppose the protest to halt oil exports.
"We can't prevent people from blockading tankers," said Colonel Abdelnasser Shalsha, army operations commander in Tobruk. "We cannot confront our own people."
His men lack the firepower to confront the protesters, he said. "We don't have any heavy guns," he said.
SPLITS AND DIVISIONS
Located closer to Egypt's Cairo than Tripoli, Tobruk has never got much attention from the capital, some 1,200 km away.
Gaddafi left schools and hospitals dilapidated in the city of 300,000 inhabitants. During his four-decade rule, there was just one weekly flight to Tobruk from the capital, according to the airport director.
Years of neglect fuel autonomy fervour among locals who were among the first to rise up against Gaddafi in 2011. One hotel carries the picture of King Idris, who created a federal system preceding Gaddafi, which many locals see as a model for their call for devolving power.
And the local museum carries a portrait of Omar Mukhtar, a freedom fighter against the Italian colonial rulers.
Talk among the crowds strolling on the central square at night quickly turns to politics and many curse the government and parliament in Tripoli.
"We want infrastructure, roads, schools," said Kamal Awad, who works at the state oil firm. "We support the oil stoppage because there is no transparency where the exports are going."
For the government and lawmakers trying to mediate the biggest question is often who to talk to.
"We are not with Ibrahim Jathran," said Abdel-Jalil al-Mazini, another Al-Abidat tribal leader who still supports the blockade. "We want the United Nations to supervise oil sales."
Mohammed Younis, a Tobruk lawmaker in the national assembly, is sceptical that future talks will even make any headway with so many protest demands.
"They all have different opinions and agendas," he said.
(Editing by Patrick Markey and Anna Willard)