* Miners trapped after shaft was hit by earth tremor
* Union, G. Fields give conflicting number of trapped miners (Recasts with Gold Fields comment, details)
JOHANNESBURG, June 21 (Reuters) - Gold Fields, the world's fourth-biggest gold producer, said on Sunday two workers were killed after a tunnel in an underground shaft caved in, trapping five miners.
The two were killed following an earth tremor of a magnitude of 3.5 on the Richter scale on Saturday morning.
The five miners were trapped when the ground fell as they were working in shaft number five of Gold Fields's Driefontein operation -- Africa's biggest gold mine.
South Africa, which has the world's deepest gold mines, has a dire safety record, and deaths from earth tremors are common in the mining industry as a whole. The incidents have led to temporary closure of shafts, denting production.
"Both of the remaining people are deceased, and their bodies have been recovered," Willie Jacobsz, a Gold Fields spokesman told Reuters.
"The entire mine has been closed for now, although it would not have been producing on Saturday evening or on Sunday anyway. We will know on Monday how long the mine will remain closed, based on a decision by the authorities."
The country's main mineworker's union gave a conflicting account of the incident at the mine located near Johannesburg.
Lesiba Seshoka, a spokesman for the National Union of Mineworkers, the country's biggest labour union, said 11 workers had been trapped at the shaft, but nine were saved.
"Two of the workers are dead, their bodies were brought to surface this morning, and nine were rescued," he told Reuters.
The Driefontein mine was hit by a tremor on June 13, which led to the death of two miners. Part of it was closed for investigations. It consists of several shafts and produced 928,000 ounces of gold in the firm's 2008 fiscal year.
Last year 168 miners died in South African mines and the government cracked down, urging the mining industry to focus on improving safety measures. It resorted to shutting mines temporarily for investigations whenever there was a fatality.
About 80 workers have died in mines so far this year. (Reporting by James Macharia; Editing by Rupert Winchester)