Wellington  - A former senior New Zealand civil servant and diplomat was officially cleared on Friday of lingering suspicion that he had spied for the Soviet Union, 33 years after his death.

Bill Sutch was charged under the Official Secrets Act but found not guilty of obtaining information that would be helpful to the enemy at a trial in 1975 after police claimed they saw him handing documents to an agent of the Soviet spy agency KGB in a Wellington street.

But he remained under a posthumous cloud of suspicion in diplomatic and civil service circles because he had travelled in the Soviet Union in the 1930s and his wide range of contacts included communists and other left wingers.

The Security Intelligence Service released its files on Sutch, an economist who was a New Zealand diplomat at the United Nations after World War 11 and later headed the department of industries and commerce, after handing them to his daughter, Helen.

"On the basis of the SIS documents released, there was no evidence to convict him in 1974 and there is none now," she told Radio New Zealand.

Helen Sutch said her father had a distinguished career and made an immense contribution to New Zealand, adding, "Our family hopes that justice can now be done to that historic legacy, which has been overshadowed for so long by events in the last year of his life."

The Sutch case occurred during the Cold War and the New Zealand SIS, like other security services in the West, kept all Soviet diplomats under close surveillance.

The file shows that SIS officers saw Sutch meet suspected KGB agent Dimitri Razgovorov three times on Wellington streets in 1974. The Russian ran away when the agents pounced and allegedly handed over a package to an embassy driver who sped off.

Documents released on Friday revealed that the SIS broke into Sutch's office and tapped his phone illegally, and then denied it to the government. (dpa)