An image grab taken from a video uploaded on YouTube showing FSA chief Riad al-Asaad reading a statement from an undisclosed location in Syria
The rebel Free Syrian Army (FSA) has announced that it has moved its command centre from Turkey to "liberated areas" inside Syria.
A video posted on YouTube appeared to show the leader of the FSA, Riad al-Asaad, confirming the move.
Gen Asaad does not say in the video when the move took place, or where in Syria the FSA's new headquarters are.
The FSA is the most prominent of the armed groups fighting to overthrow the regime of President Bashar al-Assad, reports the BBC.
Thousands of Syrians have died since the initially peaceful uprising began in March 2011, with activist groups putting the toll at over 25,000.
The FSA's move into Syria was made the previous week and "aimed to unite all rebel groups", Brig Gen Mustafa al-Sheikh of the FSA's military council told the Associated Press news agency.
In the video which appears to show him announcing the move, Gen Asaad says the FSA will fight "side by side" with "all brigades and factions" until victory.
The move is significant as the FSA has previously been criticised for leading from Turkey and being out of touch with realities on the ground, the BBC's Jim Muir in Beirut reports.
It now seems the FSA has territory it feels is reliably under their control, he adds.
The new command centre, in a secret location, will clearly be highly vulnerable to air attack by the regime - something that could increase pressure for some kind of international air cover for the "liberated areas", our correspondent says.
Meanwhile, in the northern Syrian city of Aleppo, a government offensive against districts where rebels have been operating has reportedly been continuing.
Graphic footage posted online on Saturday appears to show the aftermath of an airstrike in the Al-Missar quarter of the city.
Residents are shown trying to pull dead bodies from the rubble, including those of two young children.
The UK-based opposition group the Syrian Observatory for Human Rights said at least five people had died in a strike in Al-Missar.
Fighting was also reported by the Observatory between rebels and government forces in the western part of Aleppo province.
The city has been the scene of rebel activity and heavy government bombardment for weeks.