Trudy Crofts, 32, lost custody of her daughters Carene, 12, and Shelby, 11, seven years ago when their grandmother was appointed their guardian.

She is believed to have spirited the children out of the country in August during an access visit a week before the girls were due to return to school.

It is thought they were first taken to Spain then to Morocco where they are with her new husband’s family in Fez.

Miss Crofts, whose daughters have different fathers, is currently in prison in Madrid awaiting an appeal against proceedings to extradite her to the UK on suspicion of child abduction.

From there she telephoned her mother Rita Astbury, 54, who has legal custody of the girls, at her home in Blackpool, Lancs.

Miss Crofts is claimed to have told her: “I don’t know where the children are, but you’re not having them.”

She married her husband known as Abdullah, who she met in Blackpool, at a mosque in Spain four months ago. They have been together for over five years and lived in Blackpool, close to her mother.

Ms Astbury said: “She wants to start a new life as a Muslim. She had the kids in long clothes with wraps around them and said she had taken them to the mosque with them.”

Her daughter is thought to have flown out with the girls from Liverpool’s John Lennon airport to Spain after calling at her mother’s home and telling her: “I love you Mum.”

Officials from the Foreign Office, British Embassy and the British Consulate agreed a deal for the sisters to be returned to their grandmother last week.

But Ms Astbury said the family pulled out after receiving a message from her daughter telling them not to release the children.

Embassy officials visited the family this week and found the girls had their own bedroom and were playing out with other children.

They also obtained a telephone number for Ms Astbury, but she has repeatedly call it only to be met by a language barrier and having the receiver put down on her.

She added: “I have been told Carene want to come back with her Nan and Shelby didn’t want to speak.”

Ms Astbury was awarded custody of the girls in 2002 when her daughter was “struggling to cope” as a mother. Miss Crofts has lost three custody cases in the last five years.

”Carene and Shelby are happy girls. They are bright and they’ve got good school reports,” said Ms Astbury. “They don’t know the people they are with from Adam and nothing about the country or the culture. I still love my daughter and I always will. I’m worried about her too.”

Ms Astbury’s legal representative, Emma Schofield, said senior judge

Lord Justice Thorpe and Gordon Marsden, MP for Blackpool South, are taking up the case.

They are considering the possibility of asking Jack Straw, the Justice Secretary to seek political intervention.

Mrs Schofield said: “It seems unfair the mother is currently in prison awaiting an appeal against extradition proceedings and you’ve got two children

stranded or abandoned in Morocco.

”But because they are no longer in Europe the legal order we had for them to be returned home does not stand.

”The Foreign Office are involved and are liaising with the British Embassy and the British Consulate in Morocco.”