ALGIERS Libya's rebellion is creeping westwards from the rebel city of Misrata toward the capital along a chain of towns where opponents of Muammar Gaddafi stage clandestine night-time acts of defiance against his rule.
By day the three towns of Zlitan, Khoms and Garabulli are under government control but after darkness falls, a local man said, Gaddafi opponents daub graffiti on walls, hoist the rebel flag and the sound of gunfire can be heard.
If those acts spill over into open revolt, the three towns could act as stepping stones to allow the anti-Gaddafi uprising to spread from Misrata, the biggest rebel outpost in western Libya, to the Libyan leader's stronghold in Tripoli.
"We had never believed that these kind of cities would rise up," said the local man, who did not want to be identified because he feared reprisals for speaking to the foreign media. "There is a movement. The situation is boiling."
Three months into a revolt against Gaddafi's 41-year rule, the rebels -- with help from NATO air strikes -- have established firm control over the east of the country, the city of Misrata and a mountain range southwest of Tripoli.
Attempts to advance toward the capital have stalled though, leaving the conflict deadlocked and Gaddafi still defying international calls for him to step down.
But in the past week rebel fighters in Misrata have gradually been pushing west to within a few kilometers (miles) of Zlitan, potentially turning that town, and the towns of Khoms and Garabulli to the west of it, into the next battleground.
Accounts from the towns between Misrata and Tripoli could not be independently verified because reporters have not been given access.
Officials in Tripoli could not be reached for comment. They have previously denied there is any anti-Gaddafi unrest in areas under government control.
They say the vast majority of Libyans support Gaddafi and the trouble is being caused by small groups of armed criminals and al Qaeda militants.
Rebels in Misrata said that Gaddafi's son Khamis -- whose 32nd brigade has been deployed to put down revolts around the country and is feared by the rebels -- went to Zlitan a week ago to oversee security arrangements.
"According to information we got from people coming from there (Zlitan), the brigades have been firing on residents every now and then. They have also arrested several people over the past few days," said Abdelsalam, a rebel spokesman in Misrata.
Another Misrata rebel spokesman said government forces had positioned snipers on the rooftops of buildings in Zlitan.
NATO military spokesman Wing Commander Mike Bracken said the alliance had indications that pro-Gaddafi forces had "suppressed a number of popular... uprisings in Zlitan."
Britain's armed forces said they attacked tanks and rockets launchers near Zlitan at the weekend as part of the NATO mission to protect civilians from attack.
In the towns further west from Zlitan, the signs of unrest are more subtle, but they are unmistakable, the local man said.
In Khoms, about 25 km west of Zlitan and near the site of an ancient Roman settlement called Leptis Magna, gunshots ring out at night as security forces try to track down rebel sympathizers, he said.
"Khoms is going to explode soon," said the man, who has no involvement with the anti-Gaddafi movement.
"We have started not going out at night because it has become dangerous. Sometimes there are clashes, fighting. We don't know what will happen," said the man.
Petrol shortages were a flashpoint, he said. "There are queues at the gas stations so some people go on purpose to these stations and they start to make a noise in order to encourage people to rise up."
The rebel sympathizers, he said, have gone underground and hide out in the hills south of the town. "The government is looking for them. They know them by name but they cannot find them," he said.
Garabulli -- also known as Castelverde, the name the town was given during Italian colonial rule -- is 65 km west of Zlitan and the same distance again from Tripoli.
"I was talking to a friend from Garabulli and he was telling me that ... people in the morning found flags of the revolutionaries, the old flags, and they found something written on the walls against Gaddafi, the man said.
From Garabulli, it is another 50 km west to Tajoura, an outlying suburb of Tripoli where, early in the anti-Gaddafi revolt, large anti-Gaddafi protests were dispersed by security forces wielding Kalashnikov rifles.
Though Libyan officials deny it, Gaddafi opponents in exile say that in Tajoura too, young men come out at night to drape the red, black and green rebel flag from bridges and on public buildings.
"All the news drip-feeding out of Tripoli is pretty negative as far as the state of disarray and ... increasingly open dissent in Tripoli is concerned," said a senior diplomat from a European Union state, speaking on condition of anonymity.
"It's difficult to pin this down or to say it's going to reach boiling point any moment but the sense of the strangulation of the regime is there."