TRIPOLI, Libya (AP) -- The leaders of a movement for self-rule in oil-rich eastern Libyan unilaterally announced Thursday the formation of a shadow government, the latest challenge to the weakened central authority.

The announcement came several months after the movement, backed by some militias and local tribes, declared the eastern half of Libya to be an autonomous state, named Barqa, claiming broad self-rule powers and control over resources.

The central government in Tripoli had rejected the declaration. It had no immediate comments on Thursday.

Advocates of the self-rule in the east, who long has complained about discrimination by the government in the capital Tripoli, have been pushing for the reviving the system maintained under King Idris in 1951. Libya then was divided into three states, with Cyrenaica - or Barqa, as it was called in Arabic - encompassing the eastern half of the country.

Opponents fear a declaration of autonomy could be the first step toward the outright division of the country, particularly with the turmoil that struck in the aftermath of the fall of longtime dictator Moammar Gadhafi.

The tension between the central government and eastern militias and tribal leaders has already disrupted the exports of oil. Eastern militias earlier seized control of oil exporting terminals, sending production plunging from 1.4 million barrels a day to around 600,000, robbing the country of its main revenue source.

Abd-Rabbo al-Barassi, the head of the newly declared Barqa government, said the aim is to improve distribution of resources and undermine the hold of the centralized system that has discriminated against their region.

"The aim of the regional government is to share resources in a better fashion, and to end the centralized system adopted by the authorities in Tripoli," al-Barassi said at a news conference in the northeastern town of Ajdabiya.

He dismissed accusations that the movement's leaders are only seeking to take control of the region's oil resources. "We only want Barqa's share according to the 1951 constitution," he said.

The new government is made up of 24 posts, which don't include the defense or foreign affairs portfolios, he said. Al-Barassi said the region will encompass four provinces, including Benghazi, Tobruk, Ajdabiya and Jebel Akhdar.

Since Gadhafi's ouster following months of civil war, Libya has been beset by lawlessness as the numerous armed men who fought against the longtime leader's forces formed into independent militias now vying for power and allying with competing politicians.

"The security file will be priority," Al-Barassi said. "It is a thorny issue leading to the chaos of illegitimate militias."

It is not clear how much support the new autonomous government will have in the country's east, though the movement's leaders have seized control of important resources. Officials in the central government have threatened to use military action against any illegal or unauthorized shipment of oils.

Meanwhile, a Libyan court on Thursday referred Gadhafi's son and more than 30 others to trial before a higher tribunal on charges ranging from murder to treason during the 2011 uprising, a senior prosecutor said.

Prosecutor Al-Seddik al-Sur said the Tripoli court also decided to appoint defense lawyers for Gadhafi's son, Seif al-Islam, and the late dictator's intelligence chief, Abdullah al-Senoussi. He did not announce a date for the trial before the Criminal Court.

Al-Senoussi and al-Baghdadi al-Mahmoudi, Gadhafi's last prime minister, were among about 10 of the 38 Gadhafi-era officials to attend the hearing. Seif al-Islam, held by a militia group that captured him as he attempted to flee to neighboring Niger in 2011, was not present.

Also underscoring Libya's lawlessness since the ouster of the Gadhafi regime, gunmen shot dead an air force colonel Thursday as he left his home in the eastern city of Benghazi, the birthplace of the 2011 revolt.