Libyan government forces have been captured by Tunisian troops after crossing the border in pursuit of rebel fighters, reports say.
Tunisian TV said Libyan forces in about 15 vehicles entered the town of Dahiba before being overpowered by Tunisian troops and surrendering their weapons.
There has been fighting between Libya leader Col Muammar Gaddafi’s forces and rebels over a nearby border post.
Tunisia has strongly condemned the violation of its territory.
Analysts say the to-and-fro fighting for the crossing between Dahiba in Tunisia and Wazin in Libya is typical of the fluid and complex conflict that broke out in mid-February.
Dahiba was reported to be calm following the incursion early on Friday, Tunisian TV said.
“The violation of [Tunisian] territories by Gaddafi brigades took place this morning during their heavy fight against revolutionaries,” the report said.
“This caused violent chaos including in the centre of Dahiba. While the national army and border guards dominated the brigades and confiscated their weapons, the residents of Dahiba and the surrounding areas threw stones at the brigades’ vehicles to show that they objected to their entrance into the town.”
‘Shells fired’
A resident of Dahiba told Reuters that pro-Gaddafi forces fired shells into the town, damaging buildings and injuring at least one resident. A group drove into the town in a truck in pursuit of rebels, he said.
“The Tunisian army is combing the town. We have no idea about the fate of Gaddafi’s forces there because the Tunisian army closed the gates to the town and nobody is allowed to enter,” he added.
One report said Tunisian troops had fired into the air to disperse the pro-Gaddafi forces.
Tunisian authorities warned of a “dangerous military escalation”.
“Shots fired at a populated area on Tunisian territory [are] a violation of Tunisia’s territorial integrity and a violation of the security of the residents of this region,” a statement from the Tunisian foreign ministry said.
“Given the gravity of what has happened … the Tunisian authorities have informed the Libyans of their extreme indignation and demand measures to put an immediate stop to these violations.”
Thousands of people have fled across Libya’s borders to escape the violence of recent weeks.
In Libya itself, a rebel spokesman said Nato aircraft had hit government forces attacking the rebel-held town of Zintan.
A doctor in the rebels’ eastern stronghold of Benghazi said shelling by pro-Gaddafi forces in the besieged city of Misrata on Thursday had killed 12 people.
The claim could not be independently verified.
Nato forces have been targeting Libyan government forces under a UN mandate to protect civilians in the country.