BENGHAZI, Libya: Libya threatened on Saturday to bomb a North Korean-flagged tanker at an oil terminal in the restive east if it does not leave, saying it was loading illegally.
Separatist militants blockading Al-Sidra facility attempted to load crude aboard the Morning Glory in the latest challenge to central government control.
"The attorney general has given the order for the ship to be stopped," Prime Minister Ali Zeidan told a news conference.
"All parties must respect Libyan sovereignty. If the ship does not comply, it will be bombed," he said.
Zeidan said the authorities had told the vessel's captain to leave Libyan territorial waters, but he said armed gunmen on board were preventing him from leaving.
The self-proclaimed government of Cyrenaica in the east, the political wing of the separatists, said oil exports from Al-Sidra had now begun.
"We announce to Libyans and to the whole world that we have begun exporting oil," said Rabbo al-Barassi, who heads the Cyrenaica executive bureau formed in August by federalist activists.
"We are not defying the government or the Congress (parliament). But we are insisting on our rights," he said.
Protesters at the eastern oil ports are demanding a restoration of the autonomy the eastern region was granted in the first decade after Libya's independence in 1951.
They have also accused the authorities of corruption and are demanding a more equitable distribution of oil revenues.
Deputy Defence Minister Khaled al-Sherif told AFP a "crisis committee" of government officials and lawmakers had issued an ultimatum for the oil tanker to depart.
"If the ship doesn't comply, it will be bombed by the air force or intercepted at sea by the navy," Sherif warned.
An MP and committee member said the 2:00 pm (1200 GMT) deadline expired without any action being taken, however.
Washington's envoy to Tripoli warned on Twitter that any cargo deemed to have been loaded illegally would face international sanction.
"Companies that engage in illicit trade with separatist groups in Libya risk liability in multiple jurisdictions," US Ambassador Deborah Jones tweeted.
"The only entities authorised to sell Libya's oil are the Libyan National Oil Corp., its subsidiaries JV partners," she added.
Earlier, a member of the energy committee in Libya's interim parliament, the General National Congress, said the Morning Glory had anchored at Al-Sidra at 4:00 am (0200 GMT).
Militants seeking autonomy for Libya's east were trying to load petroleum "outside the framework of the state", he added, speaking on condition of anonymity.
Acting Oil Minister Omar Shakmak denounced the move as an "act of piracy".
"This is a violation of national sovereignty. It is up to the defence ministry to deal with this ship," he told AFP, without elaborating.
The oil crisis erupted in July, when security guards at key terminals shut them down, accusing the authorities of corruption and demanding a more equitable distribution of oil revenues.
The situation has become more complicated as self-rule activists have insisted on the right to export.
Saturday's incident was the latest in a stand-off over oil exports, the North African country's principal source of revenue.
Oil installation guards initially launched the blockade of key sites over price hikes but later also to call for autonomy for Cyrenaica, cradle of the 2011 revolt that toppled Moamer Kadhafi.
In January, the navy prevented two tankers from docking in Al-Sidra to take on crude. The government also threatened to bomb any ships attempting to dock without permission from the National Oil Corporation.
Following the blockade, production plunged to around 250,000 barrels per day from 1.5 million bpd, and the economy ministry estimated the treasury has lost more than $9 billion (6.5 billion euros) in revenue.
Production has since recovered to 546,000 bpd, but the crisis continues to take hit state coffers.
With independence after World War II, Libya was divided into three regions -- Cyrenaica in the east, Fezzan in the southwest and Tripolitania in the north.
Those regions were done away before Kadhafi seized power in 1969, but they were not forgotten.