Sasha Cameron failed to return to Scotland after a custody visit to her father Robert Cameron and his girlfriend last month and now all three have disappeared.

Descriptions of the trio have been circulated worldwide by Interpol, which is alerting police forces.

Sasha's mother, Fiona Cameron, said she does not know where her daughter is.

Police think Sahsa could be in Australia

One avenue of investigation is that the child and her father have fled to Australia, where Mr Cameron was brought up.

Mrs Cameron won custody of her three children in 1997 after a long, bitter and public court battle in both the UK and in France where she and her former husband had been living.

Sasha left home in the remote Highland village of Portmahomack, in Ross-shire, to visit her father in France on 10 July and was due back at the end of the month.

When she had not heard from Sasha, Mrs Cameron tried to call her ex-husband on his mobile phone but there was no reply

She then quickly discovered the holiday resort address he had given was false.

"I was panicking, not knowing where they had gone," she said.

"I have heard absolutely nothing from Sasha at all - not even a phone call.

"I have two children who cry every night for their sister, not knowing where she is." said Mrs Cameron.

Interpol has issued descriptions

Although she has not heard from her daughter or her ex-husband, on 12 July, the Children's Panel in Dingwall received a letter from Mr Cameron and his girlfriend Jenni Carter telling them they intended to keep Sasha.

While Interpol has alerted forces around the world, Mrs Cameron has begun her own efforts to trace her daughter.

She said: "I have been talking to friends and contacts in France and been in touch with Australia."

Residents of Portmahomack have been showing their support for the family by tying yellow ribbons - a symbol of hope - around the village.

And Sasha's classmates have made a poster with the message "Sasha, we love you".

Mrs Cameron said: "They have been marvellous. There's always people in to help and if I need anything, it's not a problem.