Kelly Rutherford has accused a judge of breaking the law by ordering her to send her children back to their father in Monaco.

The former 'Gossip Girl' star, who has been locked in a bitter custody dispute with German ex-husband Daniel Giersch over their son, Hermes, eight, and daughter Helena, six, since their split in 2008, has branded Judge Ellen Gesmer's recent ruling ''shocking, illegal and abusive'' and claims it was made ''without any legal authority.''

In a statement, the 46-year-old actress said: ''What the judge did yesterday was shocking, illegal, and abusive to my children. Without any legal authority, a judge from the lowest ranking court in the state court system violated the highest ranking federal constitutional rights of my American citizen children.

''Judge Ellen Gesmer effectively arrested my children, claiming she had authority under habeas corpus to take them into custody because of a foreign country's court order.

''Not only was there no Monaco court order registered in New York, no government official from Monaco asked the New York judge to register an order, or take any action against me or my children.

''Knowing she had no authority, Judge Gesmer seized my children and their U.S. passports, and forced them to leave the United States and reside in Monaco, a country where neither they nor I, nor even their father, has citizenship

''It was the most cruel act against a child I have ever witnessed in my entire life and the fact that it happened to American children at the hands of an American judge, in a United States courtroom is just inconceivable.''

Kelly's children had been staying with her in New York over the summer holidays and although she claims she was awarded sole custody of them earlier this year, she was forced to say goodbye to them in court yesterday (11.08.15) before they flew back to Monaco with their paternal grandmother.

The actress refused to return them to Monaco last week, as previously agreed, and Daniel accused her of child abduction.

But Kelly claims her ex-husband ''didn't care enough'' about their children to ''resolve his visa issues for three years'' or to attend the hearing himself.