Libya's deputy intelligence chief was kidnapped outside Tripoli's international airport on Sunday, a month after the prime minister was snatched by militiamen.
Mustafa Noah, the head of agency's espionage unit, was bundled into a vehicle in the car park in the capital, and had no bodyguards with him at the time, two security sources said, without giving further details on the attackers or their motives.
No group claimed responsibility for the abduction, but militias have snatched officials in the past to get political leverage. Prime Minister Ali Zeidan was briefly abducted by a militia group on the government payroll last month.
We have declared a strike for three days from today, but if our demands are not met we will continue," he said. "We will not negotiate with them. Things are as clear as the sun, we want a decision
The kidnapping comes on a day when a vast majority of Tripoli's public and private sectors went on a general strike against latest clashes.
City leaders had called for street protests and strikes at shops, schools and universities to press Libya's government to drive out militiamen blamed for the clashes on Friday and Saturday that killed at least 45 people.
The streets of Tripoli were deserted as the city's businesses and schools were closed but shops like pharmacies, hospitals and gas stations remained open.
Al-Sadat al-Badri, head of Tripoli's city council, said that the strike would last for three days, demanding an investigation into the violence.
"We have declared a strike for three days from today, but if our demands are not met we will continue," he said. "We will not negotiate with them. Things are as clear as the sun, we want a decision."
Armed residents set up checkpoints and barricades of metal, wood and tires to protect their neighbourhoods throughout the city, fearing renewed violence.
Libya's state news agency LANA said on Sunday that the Misrata militia, accused of being responsible for Friday's killing, had abandoned its headquarters in the southern Tripoli neighbourhood of Gharghour.
Late on Saturday, a government-affiliated militia, the Libya Shield-Central Command, said it was in control of Gharghour and vowed to turn it over to the government.
But in a sign of rising tensions, Misrata City leaders threatened to withdraw their members from the country's cabinet, national congress and pull back their former fighters who had been helping provide security in the capital.
"They forgot about the rebels,and so we will give the opportunity for the government to show us what will they do with the army and police," said Attia Al-Drayni, deputy head of Misrata's local council.
Violence broke out on Friday when militiamen from the coastal city of Misrata opened fire on protesters marching on their brigade quarters in Tripoli to demand they leave the capital.
Dozens of people were killed in the clashes that followed – the deadliest street fighting in Tripoli since the fall of Gaddafi in 2011. Misrata gunmen and rival militias clashed again on Saturday to the east of the capital, killing one more person, prompting authorities to declare a 48-hour state of emergency in Tripoli.
The government has tried to incorporate them into the police force and army but has failed so far.
On Sunday, a senior US military official said that the US military was working on plans to train 5,000 to 7,000 members of the Libyan security forces.
Admiral William McRaven, who heads the US military's Special Operations Command, declined to go into details about
the training plan, saying these were still being negotiated.