The National Crime Agency (NCA) had sought Unexplained Wealth Orders (UWOs) against companies which owned properties connected to Nurali Aliyev, the grandson of former Kazakh president Nursultan Nazarbayev.
But the High Court in April ruled in favour of Aliyev over the house connected to him and discharged the orders against the companies which owned the other properties. An NCA appeal against the ruling was dismissed.
"The beneficial owners and the foundations named as respondents are claiming costs totalling 1.5 million pounds," said a spokeswoman for Aliyev.
"The NCA's entire case theory, and much of its evidence, came from uncorroborated public source material," the spokeswoman said.
A spokesman for the NCA declined immediate comment.