A mother told how her heart broke when her ex-husband phoned to say he had snatched their children and they were never coming home.
Mo, nine, and May, six, were spending the weekend with their father when he failed to return them.
Two weeks on, distraught mother Claire Kielty - daughter of Brighton and Hove city councillor Gerry Kielty - spoke for the first time, pleading with her children's father: "Please bring them home to their life.
"I love them. I miss them. I want them home."
A major police hunt is under way to bring the youngsters back to their mother in Warrior Close, Portslade.
Inspector Mark Powles said: "We are concerned for the children's welfare and we need to hear from anyone who knows where they are."
He urged the father, Sudanese refugee Siddiq Ishaq: "Take the children into the nearest police station or call the police."
Mr Ishaq, 34, and Claire, 28, divorced in 1999 after six years of marriage.
The children, who attend West Blatchington junior and infant schools, were due to spend the weekend of July 12 and 13 with their father as part of a contact agreement.
Mr Ishaq picked up May and Mo, also known as Mohammed, at 7pm on Friday, July 11, and was due to return them at 4.30pm on the Sunday.
Claire received two heartbreaking phone calls that Sunday evening, telling her she would never see her children again.
Police fear Mr Ishaq might have taken the brother and sister to the Sudan.
Officers are carrying out checks with the Sudanese embassy.
Claire's father, a Labour councillor for Hangleton and Knoll, said: "This is destroying my family. I can't really believe this is happening."
Anyone with information should contact Sussex Police on 0845 6070999 or Crimestoppers on 0800 555111.
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