The wife of the Islamic State leader Abu Bakr al Baghdadi and one of his sons has been arrested at the Syrian border, say reports.
They were detained by Lebanese troops, according to security officials.
Al Baghdadi, an ambitious Iraqi militant believed to be in his early 40s, has a $10m US bounty on his head.
Since taking the reins of the group in 2010, he has transformed it from a local branch of al Qaeda into an independent transnational military force.
He has positioned himself as a leading figure in the global jihadi community.
A US-led coalition has been launching airstrikes on IS militants and facilities in Iraq and Syria for months.
The strikes are part of an effort to give Iraqi forces the time and space to mount a more effective offensive.
IS had gained ground across northern and western Iraq in a lightning advance in June and July, causing several of Iraq's army and police divisions to fall into disarray.
