CORRECTED - CORRECTED-Hyundai, Kia unions stage partial strike

(Corrects an estimated production loss to 124.8 billion won from 91.4 billion won in para 3)

SEOUL, July 18 (Reuters) - Unionised workers at Hyundai Motor Co (005380.KS) and affiliate Kia Motors Corp (000270.KS), together the world's No.5 automaker, on Friday launched a partial strike over a wage deal, the unions and companies said.

Both day and night shift workers at South Korea's top two carmakers plan to stage six-hour walkouts and to reject overtime work.

The labour actions will cause the companies to lose a combined 124.8 billion won ($121.5 million) in production, Hyundai Motor Group officials estimated.

Unionised workers at the automakers have staged partial strikes for four days this month, costing Hyundai and Kia a total of 341.7 billion won in production, according to company data.

But the losses are usually made up by overtime work after the unions and the management agree on a wage deal.

Shares in Hyundai rose 0.15 percent to 68,600 won and Kia gained 2.23 percent to 11,450 won as of 0232 GMT, compared to a 0.28 percent gain in the wider market . ($1=1026.7 won) (Reporting by Park Ju-min and Cheon Jong-woo; Editing by Jonathan Hopfner)