The world's fourth-biggest gold producer, Gold Fields Ltd, posted a 42 percent gain in fourth-quarter profit on Thursday, boosted by bullish gold prices but still sharply below analysts' forecasts.

South Africa's Gold Fields said adjusted earnings per share, excluding the effects of financial instruments and foreign debt, for the three months to June rose to 108 South African cents from 76 cents in the previous quarter.

The firm was expected to post a 76 percent rise in EPS to 134 cents, according to the average estimate of eight analysts polled by Reuters. Their estimates were in a range of 114-173 cents.

"In general it is a very poor showing," said analyst Leon Esterhuizen at Investec Securities in Johannesburg.

"It's really all about operational performance that's lagging. South African production was essentially flat while the offshore production was volume-wise flat with grades declining."

Output should have increased since traditionally the first three months of the year are the worst, he added.

Gold Fields shares, which have gained 35 percent so far this year, rose 1.27 percent to 155 rand by 0719 GMT, outperforming a 0.89 percent rise in the gold mining index.

PRODUCTION EDGES LOWER

Production was barely changed at 1.018 million ounces, down from 1.023 million last quarter, with output up 4 percent at South African operations and down 7 percent at international mines.

A rally in the gold price, which has surged 50 percent over the past 12 months and 26 percent since the start of the year, was a key reason for the jump in profits.

Gold Fields sold its gold for 128,974 rand per kg, up 18 percent from the previous quarter while total cash costs rose by 5.2 percent to 77,187 rand per kg.

"We are particularly pleased that we have been able, through effective cost control, to see a significant part of the higher gold price flow through to the bottom line," Chief Executive Ian Cockerill said in a statement.

Gold Fields -- which operates mines in South Africa, Ghana, Australia and Venezuela -- along with rivals has been fighting sharply rising prices for inputs due to a global surge in mining activity.

The firm said operating profit rose 40 percent to 1.66 billion rand while the group operating margin increased to 38 percent from 32 percent.

Gold Fields said production for the first quarter to the end of September was expected to be "marginally higher" than for the June quarter. "Total cash costs should also increase due to the wage increases at South African operations," it said.