An international controversy has blown up over the adoption of two six-month-old twin girls, who were sold twice by an Internet adoption agency in the US. An American couple first bought the twins for £4,000, but they were later abducted by their birth mother and sold again to a British couple for twice as much. The original adoptive parents say the British parents have no legal right to the children and have called in the FBI to help with their investigation. The case highlights the growing use of the Internet in creating an international trade in children. Both sets of parents reportedly set up the adoption process through an online broker called Caring Heart Adoption, which has since disappeared. While most adoption sites might be above board, legal complications arise from unscrupulous deals. The Internet also raises the additional complication of international law and local jurisdiction. In the adoption business as in any other, the Net helps smaller operators to establish an international presence. "It does make it easier," says Robin Bynoe, partner at City law firm Charles Russell. "If this is done over the Internet, a lot of the preliminary stages can be dealt with at arm's length. It's a matter of practicality." Richard and Vickie Allen of San Bernardino originally adopted the twins, known as Belinda and Kimberley, from mother Tranda Wecker, 28, a hotel receptionist from St Louis. They raised the children for two months before Wecker snatched them back, under the pretext of a farewell visit. Wecker then sold the children to British couple Alan and Judith Kilshaw for £8,200, meeting in a California hotel room. After an encounter with the Allens, the Kilshaws took the children to Arizona, where they adopted them under state law. Belinda and Kimberley are currently in the UK under six-month tourist visas and are waiting for confirmation of the adoption by British authorities. The Allens claim the Kilshaws have no right to the twins, and could bring a court battle to the UK. But the Kilshaws may have the stronger claim since the Allens had not yet completed the legal adoption process in California. The Kilshaw family claims they discovered Caring Heart Adoption online, but made all the arrangements by telephone. Bynoe said the difficulties of adoption under English law -- which is particularly tough on couples wishing to adopt a child of a different race -- lead many to adopt abroad. The adoption of Belinda and Kimberley would have been unlikely in the UK, for example, because they are of mixed race while the Kilshaws are white. A number of Web sites have sprung up around the adoption business, some catering specifically to an international market. Sites such as Adoption.com have extensive photographic listings of children, while Adoption Travel helps adoptive parents arrange international travel. The UK's first online adoption appeal, on the Derbyshire County Council's Web site, went live in 1999. Have your say instantly, and see what others have said. Click on the TalkBack button and go to the ZDNet News forum. Let the editors know what you think in the Mailroom. And read other letters.