Britain's regulator lost its first criminal case for insider dealing on Thursday as a jury acquitted a lawyer and a finance director of wrongdoing and a second lawyer had charges against him dropped.

The Financial Services Authority had charged Andrew King, a finance director, and lawyers Michael McFall and Andrew Rimmington with eight counts of insider dealing during the 305 million pound ($450 million) takeover of biotech firm NeuTec Pharma by Swiss drugmaker Novartis.

But in a blow to the regulator, the jury dismissed the charges against McFall -- a former partner at law firm McDermott Will & Emery -- and King, the former finance chief at NeuTec.

Rimmington, a former partner at law firm Dorsey & Whitney, was discharged by the judge half-way through the trial for personal reasons. His brother had been assaulted and killed and the FSA said it was not pursuing him separately.