Michael Brown waived an extradition hearing after he was flown from his villa on Majorca to a Madrid jail, The Times of London reported.
Brown, although living abroad, was a major financial backer of the Liberal Democratic Party. His record 2.4 million-pound ($4.3 million) gift helped the party win its largest ever number of parliamentary seats in the last election, but the donation is now under investigation and might have to be returned if the company that was the actual giver is shown not to be in business in Britain.
The criminal charge involves a financial dispute with HSBC Bank. The charges include forgery, perjury, perverting the course of justice, false accounting and obtaining a passport by deception.
The Times, citing sources close to Brown, said the case involved an investment with a consortium including former Manchester United chairman Martin Edwards. In a statement, one of Brown's assistants said the financier expects the case to be settled soon.