UPDATE 1-S.Africa gold firms slightly raise wage offer

* Companies up offer to 9.5 percent for lowest earners

* Union says offer still not enough

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JOHANNESBURG, July 13 (Reuters) - South African's Chamber of Mines raised its wage raise offer to mineworkers from 9 percent to 9.5 percent for the lowest earners on Monday but it may not be enough to avert a strike, a mineworkers union said.

"That is definitely not enough and we'll have to take this through to our members to decide whether we'll need to get a certificate ... which will enable us to strike," Lesiba Seshoka, spokesman for the National Union of Mineworkers (NUM) said.

Three South African unions are holding talks with gold producers under the guidance of a mediator after failing to agree on wage increases, and the unions have warned they could strike if they fail.

The talks are being watched closely by markets because a strike could affect production, mining shares or metal prices.

AngloGold Ashanti (ANGJ.J) and Gold Fields (GFIJ.J) last week made an improved offer of a 9 percent increase on the lowest earners and an 8 percent rise for the rest of the workforce, up from a previous offer of 7 percent for all staff.

"We call on the employers to stop dilly-dallying. They must move beyond a double digit figure," Seshoka said.

Mine workers, whose lowest-earning members earn 3,300 rand ($398.6) a month, have demanded a 15 percent pay rise, arguing the price of gold is up despite the global economic downturn.

But gold firms say they can't afford the increase, which is nearly twice South Africa's consumer inflation of 8 percent.

South Africa is the world's No. 3 gold producer, and the mining sector is subject to intense scrutiny by big foreign groups such as Anglo American Plc (AAL.L), South Africa's biggest mining player.

Its industrial sector is well developed, making it the biggest economy in Africa. (Reporting by Muchena Zigomo)