UPDATE 1-Worker dies at Harmony Gold's mine in S.Africa

* Unclear what killed worker

* Harmony says production not affected

(Adds output ongoing)

JOHANNESBURG, July 3 (Reuters) - A worker died at Harmony Gold's (HARJ.J: Quote, Profile, Research) Phakisa mine in South Africa, with the cause of death yet to be determined, and gold production was unaffected, the company said on Friday.

The fatality at the mine in the Free State province occurred early on Friday, and investigations into the cause of death, including an autopsy, would take place, Harmony said.

Government inspectors visited the shaft where the worker was found lying dead early on Friday and gave the go-ahead to proceed with mining.

"Investigations into the incident are under way. Safety will continue to receive priority attention at all Harmony's operations," said Chief Executive Officer Graham Briggs.

South Africa, which has the world's deepest mines, has one of the highest rates of work-related mining deaths in the industrialised world. Last year 168 workers died in legal operations, down 24 percent from the previous year 2007 when 221 fatalities were reported. (Reporting by Agnieszka Flak and James Macharia)