Fighters from across Libya flooded into the capital in late August to help overthrow Gaddafi's 42-year regime and many have stayed put, provoking concern among many residents and raising fears over the capital's future stability.
Militia fighters from cities such as Misrata and Zintan man checkpoints around the city, wander the streets with automatic rifles and speed through city roads in pick-up trucks mounted with anti-aircraft guns.
Residents blame them for eruptions of automatic gunfire that still echo through the streets of Tripoli every night.
"It's time for these people to go home. They do not belong here," Tripoli resident Hamza Bonwara, 27, told AFP as he strolled with friends around the capital's Martyrs' Square, renamed from Green Square after Gaddafi's ouster.
"They don't care about Tripoli. They are always carrying their guns around and firing them into the air -- It's dangerous and it frightens people," he said. "It is peaceful in Tripoli now, why do they need to stay?"
Some in Libya's ruling National Transitional Council (NTC) have called on the fighters to go home, but others say their presence is still needed to ensure security in the capital.
NTC spokesman Jalal el-Gallal said the regional fighters are necessary, for now, to help secure Tripoli and will be replaced by local security forces when that becomes possible.
"These are valid concerns, but at the same time we don't want to create a void" in security by ordering them to leave, he said.
"Nothing should be done in a rush," he said. "They will withdraw, as to when and how, that is being discussed."
Gallal said it was unclear how many regional fighters were in the capital, but that "the number is in the hundreds, not the thousands."
It was also unclear how much effective control the NTC was exerting over the many different militia groups -- a fact that has raised concern among the new regime's foreign allies.
Visiting Tripoli this week, US Senator John McCain said: "It's important for the (NTC) to continue bringing the many armed groups in this city and beyond it under the responsible control of its legitimate governing authority."
Regional fighters in the city defended their presence, saying they were only in the capital to provide security and protection.
"There are not enough fighters from Tripoli to protect the city so we need to be here," said Siraj Alsak, a militia member from the town of Gharyan about 85 kilometres (50 miles) from Tripoli, as he sat in a pick-up truck guarding Martyrs' Square.
Nearby, however, residents made it clear the fighters were no longer welcome.
"We are grateful for the support they gave us against Gaddafi, but it is time for them to leave," said Nadir Mohammed, 34.
"There are enough people here to protect the city. We also fought against Gaddafi, we can take care of Tripoli."
Shopping with friends at a market close to the square, Maria Gerguri, 20, said she was increasingly afraid of the many armed fighters roaming the streets.
"Why do they need to be here? The government needs to make sure they go home," she said. "They are welcome in Tripoli, but not as long as they carry guns."