JOHANNESBURG (Reuters) -- South Africa's main inflation rates are expected to have dipped in September on lower fuel and electricity prices, but the reprieve is unlikely to ward off further interest rate hikes.

The annual increase in the targeted CPIX inflation index is likely to have remained steady at 5 percent last month, but headline inflation and factory gate prices are forecast to have fallen, according to a Reuters poll of 15 economists.

Consumer price figures are expected to show a year-on-year headline inflation of 5.2 percent compared with 5.4 percent in August, when interest rates rose by half a percentage point.

South African Reserve Bank Governor Tito Mboweni hiked interest rates for the third time earlier this month, and warned that CPIX would accelerate to the upper end of the band, reinforcing predictions of more rate increases. Most economists see another two half percentage point rise in rates in the current cycle to cool inflation.

Producer prices are likely to have retreated from a 3-1/2 year peak scaled in August, due largely to lower electricity costs after a return to summer season rates.

The index, is forecast at 9 percent in September, down from 9.2 percent, the poll showed.

"For the immediate future... we expect next week's inflation data to show a moderation in inflation in September on the back of seasonally lower electricity prices and the decline in fuel prices," Elna Moolman, economist at Standard bank, said.

Factory gate prices have shocked the market on the upside over the past few months, and together with record credit extension, have been a major concern for the central bank.

A fall in the value of the rand currency of about 16 percent against the dollar this year has added to pressure on imported goods inflation, which is expected to filter through to CPIX inflation in the coming months.

Petrol pump prices dropped by 5 percent in September off a record high and fell by an even larger margin this month, pointing to a reduced threat from what has been one of the driving forces in rising inflation.

But increasing food costs remain a concern and should continue to add to inflation.

"There is pressure from food prices and we are seeing some pressures from administered prices going forward," said Citadel economist Salomi Odendaal.

Credit extension and money supply figures, due on Oct. 30, are forecast to remain high, although the credit number was likely to be down from a record 25.03 percent in August. Economists expect year-on-year growth in credit extended to the private sector of 23.9 percent in September, with money supply marginally higher at 21.86 percent, from 21.35 percent previously. "Credit extension has been growing very strongly for a long time and we see a slight dropping off in that growth rate ... the interest rate hikes should slowly start to work through to the credit numbers," Odendaal said. South Africa's notoriously volatile trade balance, due on Oct. 31, should stay in deficit of around 3 billion rand compared to 5.3 billion rand in August and a record 7.75 billion rand in July. The trade gap has helped push the deficit on South Africa's current account above 6 percent of gross domestic product, weighing heavily on the rand and fanning inflation.