LONDON – JPMorgan Chase’s London unit has been fined a record $48.6 million by Britain’s financial regulator for not properly separating client money from the firm’s accounts.

An average of $8.6 billion wasn’t properly segregated by JPMorgan Securities in an error that went undetected for seven years, the Financial Services Authority said in a statement Thursday. As much as $23 billion of client money held by the bank’s futures and options business wasn’t put in separate overnight customer accounts between 2002 and 2009, the FSA said.

The bankruptcy of Lehman Brothers Holdings, which roiled financial markets worldwide in 2008, forced the FSA to put financial companies on notice that they must properly separate client funds. New York-based Lehman’s creditors filed more than $830 billion of claims and regulators worldwide are trying to unravel how money moved through its global units.

“The FSA has repeatedly emphasized the importance of ensuring that client money is adequately protected,” said Margaret Cole, the FSA’s enforcement director. “This penalty sends out a strong message to firms of all sizes that they must ensure client money is segregated in accordance with FSA rules. Firms need to sit up and take notice of this action — we have several more cases in the pipeline.”

Had the company gone bankrupt, clients could have lost their money as unsecured creditors rather than having the right to claim back money from ring-fenced accounts.