Photos shared on social media purported to show armed gunmen in technicals posted up around the offices of Prime Minister Abdul Hamid Dbeibeh, leader of the Government of National Unity.
Video purported to be of the gunmen at the site was also shared on social media, along with footage of the technical convoy on the highway.
According to Al-Arabiya, power has been cut to the building as well.
Sky News Arabia reported that Salah Badi, leader of the Al-Samoud Brigade militia, announced on Wednesday night that there would be no presidential elections in Libya and the UN-sanctioned group would close all state institutions in Tripoli.
Elections are presently scheduled for December 24, but earlier on Wednesday, the head of the Interior Affairs Committee in the Libyan House of Representatives warned the country wouldn't be ready to hold elections by then and called on the government to accept the situation. Russian Foreign Minister Sergey Lavrov said earlier that a postponement of the elections would be acceptable provided the outcome is accepted.
The move comes after Mohammed Menfi, leader of the Presidential Council that functions as Libya's head of state and supreme military commander, dismissed the head of the Tripoli Military District, Maj. Gen. Abdul Basit Marwan earlier on Wednesday.
According to Al-Marsad, the Libyan News Observatory, which cited unnamed sources, the military movements are part of a plan orchestrated by Menfi to issue a presidential decree on December 23 and form a mini-government.
The civil war in Libya has raged since a NATO-backed coup overthrew, tortured and executed Libyan leader Muammar Gaddafi in 2015. A March 2021 agreement saw the country's two primary factions - the UN-backed government in Tripoli and the Libyan National Army in Tobruk - agree to form a Government of National Unity as a step toward the elections scheduled for December.
On Sunday, the supreme commanders of the two sides' armed forces met in the central city of Sirte and agreed to unite into a single military force.