Sudan's President Omar al-Bashir has expressed concern about instability in neighboring South Sudan and other volatile states in the region, official media reported Sunday.

Bashir "expressed his concern about what is going on in South Sudan, Central African Republic, Libya and Egypt,” the state SUNA news agency reported.

A suicide bomber rammed an explosives-laden vehicle into a security checkpoint outside eastern Libya's restive city of Benghazi overnight, killing at least 13 people, the government said Sunday.

The country's weak post-revolutionary authorities, who have struggled to stem unrest since the 2011 uprising that toppled strongman Moammar Gadhafi, called for three days of national mourning and denounced the "terrorist attack."

Britain, the United States and Libya issued a joint call Saturday for justice over the Lockerbie bombing as services were held to mark the 25th anniversary of the attack, which claimed 270 lives.

The three governments gave their "deepest condolences" to relatives of those who died when Pan Am Flight 103 blew up over the Scottish town of Lockerbie on December 21, 1988, en route from London to New York.

Libyan Oil Minister Abdelbari al-Arusi on Saturday issued a renewed threat of force to lift a months-long blockade of oil terminals by striking autonomists.

"The government is making every effort to hold talks with those blockading the terminals," he told journalists on the sidelines of a conference in Doha of the Organisation of Arab Oil Exporting Countries.

The head of military intelligence in the eastern Libyan city of Benghazi was shot dead on Friday during a visit to his family in nearby Derna, a security official said.

"Unknown assailants opened fire at Colonel Fethallah al-Gaziri, head of Benghazi military intelligence, and killed him," the official told Agence France Presse on condition of anonymity.

A bomb killed an electrical power plant manager Thursday in eastern Libya, while authorities also found the head of a man who had been kidnapped for ransom.

Adam al-Mansouri was killed when a bomb placed under his car exploded in the city of Tobruk, near the Egyptian border, a local official said.

Few Libyans have registered to vote for a constitutional commission, official figures showed Tuesday, as the country grapples with growing unrest two years after the toppling of Moammar Gadhafi.

The High National Election Commission's website said only 436,000 Libyans had signed up out of a total electoral list of 3.4 million ahead of a December 21 deadline.

Libya has blocked a U.N. plan to send more than 200 soldiers to the troubled country to guard U.N. staff, diplomats and officials said Monday.

The United Nations leadership received backing from the U.N. Security Council last month to to send a 235-strong guard force because of the mounting threat of attack on the U.N. mission in Tripoli.

Libyan coastguards rescued 92 African migrants stranded at sea when their boat broke down off the Tripoli coast as they were trying to reach Europe, Lana news agency reported.

The operation off the Al-Buri oilfield brought 92 migrants from various African nationalities safely to shore, Lana said, quoting navy spokesman Colonel Ayyub Amor Gacem.

An army officer was killed and three soldiers were wounded Sunday in Libya's lawless eastern city of Benghazi, security and medical sources said.

"Unknown gunmen opened fire at Colonel Saad al-Jamli as he dropped off his son at a school in central Benghazi," a security official told Agence France Presse.