Foreign Office officials said they have been in touch with Egyptian police about the case of a 12-year-old British girl who went missing more than seven years ago and is thought to be living in Cairo.
Elsa Salama is at the centre of a battle between her divorced parents in the family court in London.
Egyptian former teacher Tamer Salama took Elsa, then four, from her mother, Naomi Button, in December 2011 while all three were visiting his relatives in Egypt.
Ms Button, a leadership consultant from Leeds, was forced to return to England alone and has not seen Elsa, who is thought to be living with Salama’s mother in Cairo, since.
She launched family court litigation after arriving back in the hope of getting Elsa home and is continuing that fight.
Salama, who subsequently returned to England without Elsa, was jailed in January 2012 for breaching judges’ orders to arrange his daughter’s return to England or to reveal where she was.
But a judge ordered his release in December 2013 after deciding that continuing to keep him in prison was no longer proportionate or justifiable.
A judge overseeing the latest stage of the litigation has asked Foreign Secretary Jeremy Hunt for help.
Mr Justice Mostyn said on Tuesday that he wanted Mr Hunt to use all “diplomatic measures” to try to trace Elsa.
A Foreign Office spokeswoman said on Wednesday that officials have been in contact with Egyptian police.
Mr Justice Mostyn has described Ms Button and Elsa as being the victims of “formidable” cruelty.
He said, in a ruling published on Tuesday following a recent hearing in the Family Division of the High Court in London, that it was hard to imagine the “daily agony” Ms Button must endure.
Salama has said he does not know where Elsa is.
The judge said he was “absolutely sure” that that statement was “completely false”.
A Foreign Office spokeswoman said: “Our staff have offered advice to the family.
“We have been in contact with the UK and Egyptian police about her case.”