Libyan soldiers have been stationed at Tripoli's main square to protect a rally in support of the government that was planned for Friday afternoon, a source at the prime minister's office said.
"They are expecting to have some demonstrations and I would expect it's because they want to protect the demonstrators,'' the source said.
A defense ministry source said the order came from the prime minister's office.
Reuters witnesses saw the soldiers on the square as well as on the main road to the airport.
Armed militia targeting Libya's ministries and media in the capital this week have alarmed international observers who say deteriorating security conditions are becoming a matter of serious concern.
Gunmen in heavily armed vehicles were in control of Libya's Foreign Ministry for a sixth day on Friday. The Justice Ministry was also surrounded.