Eastern Libya has declared an autonomous regional government with an official ceremony, challenging the country's weak central government that failed to assume unifying power over rebels and various tribes since the 2011 war toppled Muammar Gaddafi.

Leaders of an autonomy movement met on Sunday in the small town of Ajdabiya to launch the government under the name of Barqa, or Cyrenaica as it is also known, supporters said.

A pro-federalist television station showed more than 20 ministers taking the oath at a podium decorated with a Cyrenaica flag.

They were joined by the tribal leader Ibrahim Jathran, the former head of Libya's Petroleum Protection Force in charge of guarding oil facilities, who defected in the summer and seized the biggest ports Ras Lanuf and Es-Sider with his troops.

Jathran was standing next to the self-declared Prime Minister Abd-Rabbo al-Barassi, a defected air force commander.

Symbolic blow

The announcement is a symbolic blow to efforts by the Tripoli government to reopen eastern oil ports and fields blocked since summer by rebels and tribes demanding a greater share of power and oil wealth.

It has no practical meaning, but is sure to worsen ties between the east and Tripoli, which has rejected the self-rule notion.

Officials were not immediately available for comment.

Lawlessness has blighted large areas of the OPEC producer since ousting Gaddafi in 2011. The government has been unable to rein in rebel groups and armed tribes.

Prime Minister Ali Zeidan had been seeking contact with the east in the past few days trying to reopen blocked oil ports in an area home to 60 percent of the country's oil production.

The protesters and strikes at ports and oil fields have knocked down crude production to some 10 percent of Libya's capacity of 1.25 million barrels a day.

The North African country used to pump 1.4 million bpd until the strikes started.