Iraq's Interior Ministry said on Wednesday that a woman detained by Lebanese authorities was not the wife of Islamic State leader Abu Bakr al-Baghdadi, but the sister of a man convicted of bombings in southern Iraq.

"The one detained by Lebanese authorities was Saja Abdul Hamid al-Dulaimi, sister of Omar Abdul Hamid al-Dulaimi who is detained by authorities and sentenced to death for his participation in ... explosions," ministry spokesman Brigadier General Saad Maan told Reuters.

"The wives of the terrorist al-Baghdadi are Asmaa Fawzi Mohammed al-Dulaimiand Esraa Rajab Mahel al-Qaisi, and there is no wife in the name of Saja al-Dulaimi," he said.

Maan said Saja Dulaimi had fled to Syria where she was detained by authorities. She was part of a group of female detainees freed in exchange for the release of a group of nuns captured by Islamist rebels in Syria, he said.

Security officials in Lebanon said on Tuesday the Lebanese army had detained a wife and daughter of Baghdadi's as they crossed from Syria late last month.

They were detained in northern Lebanon after the woman was found with a fake passport, officials said. Investigators were questioning her at the Lebanese Defence Ministry.