Two surgeons have been cleared of manslaughter after their patient died following an operation during which they mistakenly removed his only healthy kidney.

Consultant urologist John Roberts and surgeon Mahesh Goel were acquitted on the direction of the judge after the crown prosecution service decided it could not prove that any action or omission by either surgeon was a more than minimal cause in the death of Graham Reeves in March 2000.

Both had denied the charge and pathologist Andrew Davison told Cardiff crown court yesterday he could "not be sure" the man had died as a result of the operation.

Mr Reeves, a retired pipe lagger and war veteran from Burry Port, west Wales, died five weeks after his functioning left kidney was removed instead of his right, which was chronically diseased and had not functioned for years.

The operation had taken place at Prince Philip hospital, Llanelli, and Mr Reeves died five weeks later at another hospital in Swansea. The prosecution had argued earlier that negligence on the part of each "was so bad - fell so far below the standard of care to be expected of a competent surgeon - that it deserves to be condemned by you as amounting to gross negligence".

Both surgeons were suspended following the incident, and Mr Roberts remains suspended, Carmathenshire NHS trust said last night. Ian Barker, of the Medical Defence Union, which represents Mr Roberts, said the consultant was "profoundly sorry" about the death of Mr Reeves. "Something positive may come from this tragedy if the publicity attached to it allows others throughout the country to learn lessons that similar tragedies can be avoided in future."

The court had heard that Mr Roberts, 60, had overseen the operation, and that Mr Goel, 40, who no longer works for the trust, had carried out the procedure on Mr Reeves, then 69.

The NHS trust said that procedures in place at the time of Mr Reeves's death had been found to be effective by two independent audits. "The trust wants to point out that evidence was also given in court that the x-rays used during Mr Reeves' operation were properly marked. The trust's nursing and support team acted according to the correct procedures."