The billionaire Tchenguiz brothers have been ordered to pay their brother-in-law an additional £100,000 towards his legal costs after failing to meet a previous court order.

The High Court ruling this week is the latest twist in a bitter dispute between Robert and Vincent Tchenguiz and Vivian Imerman, their brother-in-law and business partner.

Mr Imerman, the former owner of Whyte & Mackay, the whisky distiller, is married to the Tchenguizes’ sister, Lisa, who has filed for divorce.

In August, Robert and Vincent were ordered to return confidential documents seized from Mr Imerman after his marriage began to unravel. Robert told the High Court he took the documents because he feared Mr Imerman would seek to disguise a £500 million fortune during divorce proceedings.

In addition to ordering that the documents be returned, Mr Justice Eady ordered the Tchenguiz brothers to pay £150,000 towards Mr Imerman’s costs by September.

Despite several demands from Mr Imerman’s lawyers, the brothers did not pay the money, leading Mr Imerman to launch further proceedings. Mr Justice Eady ruled in favour of Mr Imerman in the supplementary proceedings and again ordered the Tchenguiz brothers to pay his costs.

The judge ordered the brothers to pay the original £150,000 plus 8 per cent interest to the court as well as an additional £100,000 in legal costs to Mr Imerman. The total legal bill for the dispute is likely to exceed £1 million, which the losing side may be ordered to pay in full.

The Tchenguiz brothers plan a further appeal this week.

Mr Imerman declined to comment. A person close to the Tchenguiz brothers said that they would be “vigorously pursuing the appeal”.

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