By Heekyong Yang

SEOUL (Reuters) -Kia Corp's unionised workers in South Korea will go on a partial strike for six working days from Oct. 12 after three months of talks with the company stalled over wage increases and an extension of the retirement age, the company's union said. The union said it had decided to suspend work for a part of each day until Oct. 20, in what would be the first industrial action at Kia in three years.

Last month, the union at South Korea's No.2 automaker with more than 26,600 members said 92.3% of its members had approved strike action unless the management accept the demands.

The labour action at Kia comes as the union at affiliate Hyundai Motor Co avoided a strike after the union and the management last month sealed a deal set to boost annual pay by about 12%.

The Kia union is seeking a minimum basic monthly pay increase of 184,900 won ($138.12), a performance pay equating to 30% of Kia's 2022 net profit as well as an increase to the retirement age to 64 from 60 and a 4-day work week.

The union said it would work regular hours on days when they are holding talks with the management. The union and the management have had 14 rounds of talks since July.

Kia declined to comment on the strike.

Because the deals with Hyundai Motor and affiliate Hyundai Mobis were concluded without any industrial action, Kia's unions are likely to avoid any major industrial action, analysts said.

"For now, Kia is the only one that plans to go on an actual strike... this is unlikely to give much momentum for Kia to carry intense strikes or go on for too long by itself," said Lee Jae-il, an analyst at Eugene Investment & Securities.

Shares in Kia Corp were trading up 0.7%, versus the benchmark KOSPI's 2.1% rise as of 0217 GMT.

(Reporting by Heekyong Yang; Editing by Edmund Klamann and Miral Fahmy)