LONDON The British couple at the center of a tug-of-war over adopted twin baby girls have been ordered to appear in a U.S. court to answer charges of abduction, the BBC reported on Friday.

Judith and Alan Kilshaw were served with a writ moments after appearing on the Oprah Winfrey Television chat show in Chicago with rival adoptive parents Richard and Vickie Allen, according to the report.

The Kilshaws, from Buckley in North Wales, were quoted by the BBC as saying they were "horrified" by the court order but intended to fight it.

The writ was served by lawyers acting for the Allens, from San Bernadino, California. They claim they were about to finalize adoption procedures for the twins when an Internet adoption broker allegedly abducted them and sold them to the Kilshaws for a higher fee.

Under the terms of the writ, the Kilshaws must appear before a court in the U.S. State of Arkansas, said the BBC.

That was where they had the twins' adoption papers processed late last year.

The two couples are at opposite ends of a morally unsettling tug of war over the seven-month-old girls which has spotlighted problems related to adoptions brokered over the Internet.

Both the Kilshaws and the allens were allegedly promised the girls by adoption broker Tina Johnson contacted over the web, and after paying thousands of dollars in fees.

The girls, who now go by the names Belinda and Kimberley, were originally placed with the Allens.

But the girls' biological mother, Tranda Wecker, took them from the Allens' home and without warning allegedly handed them over to the Kilshaws in San Diego, California. After moving to Arkansas where they completed adoption papers, the Kilshaws then flew back to England with the girls.

The Kilshaws handed over 8,000 pounds (12,500 dollars) to Johnson and her web adoption agency, a caring heart, which is based in San Diego County.

The Allens parted with about half that sum.

In a new twist to the saga, there have been suggestions that the Kilshaws' adoption of the girls was invalid because wecker allegedly lied on adoption forms.

While the legal mess is being sorted out a British judge ordered that it was in the girls' best interests for them to be put into foster care.

Police and social services last month seized them from a hotel in North Wales where the Kilshaws were staying.

Lawyers for the Allens served the writ on the Kilshaws at the end of an angry televised confrontation between the two couples.

Winfrey, sitting between them on a television studio stage, adjudicated as they each claimed they were the rightful adoptive parents of the two girls.

A combative Judith Kilshaw, 47, repeatedly asked the allens: "Did you actually adopt them?" Richard Allen said that what mattered most was that the argument was resolved in the best interests of the twins. He said he had "no beef" with the Welsh couple."