Three Bradford sisters and their nine children have "crossed into Syria", according to an Isis smuggler.
Khadija Dawood, 30, Sugra Dawood, 34, Zohra Dawood, 33, and their children failed to return to the UK last week following a trip to Saudi Arabia, and it was feared they had traveled to Isis-controlled territory.
A smuggler who runs the militant group's border operations has told the BBC the family arrived in Syria on Wednesday and Thursday, having been split into two groups.
One of the sisters has made contact with family in the UK, and early this week two of the women's husbands made an emotional plea for their return.
Akhtar Iqbal, who is married to Sugra and father to five of the children taken to Syria, said: "I am shaking. It's been too many days. Please come back home. I love you. All of you."
The sisters are believed to be trying to join their younger brother, Ahmed, who left Britain in 2013 to join extremists and was already under police investigation.
Authorities are looking into whether the women made the journey after communicating with Ahmed, 21, over Skype.
Assistant Chief Constable Russ Foster, of West Yorkshire Police, this week said: “Contact has been made by one of the missing women and there is an indication that they may have already crossed the border into Syria, but this is uncorroborated. We are extremely concerned for the safety of this family.”