The death of former Pakistani dictator General Zia-ul-Haq in a mysterious plane crash in 1988 was not due to any technical fault, a senior official has said.

"It was not a technical problem," Technical Investigator Naseem Ahmad said at a workshop on Thursday regarding the crash of a C-130 Hercules military aircraft in 1988 that killed Gen Zia, US Ambassador Arnold Raphel and over two dozen senior military officers.

Naseem, who was addressing a media training workshop on the investigation of aircraft accidents organised by the Civil Aviation Authority, said around 82 per cent of aircraft accidents occurred due to human error and not technical problems.

However, he did not say that Gen Zia's plane crashed due to human error.

Naseem said that aircraft have no upper life limit because air-worthiness determines a plane's suitability for flights and most parts of aircraft could be replaced with new ones.

Since the crash, there have been various conspiracy theories about it. Many people in Pakistan believe foreign intelligence agencies were involved in the incident.