* Foreigners sell for fifth day
* SK Telecom falls almost 4 pct on earnings woes
* Techs mostly down by LG Elec bucks market
* Kaesong-related stocks plummet
By Somang Yang
SEOUL, April 9 (Reuters) - South Korean shares were slipping to another four-month low on Tuesday as tensions with North Korea and a weaker yen that would make Japanese exports cheaper weighed on investors.
The Korea Composite Stock Price Index (KOSPI) ticked 0.5 percent lower at 1,909.27 points as of 0247 GMT.
"The index is struggling to stay steady, amid foreign selling, as the yen approaches 100 against the dollar and the risks with North Korea loom," said Shim Jae-yeob, an analyst at Shinhan Investment Corp.
The dollar rose to as high as 99.67 yen on trading platform EBS, the greenback's strongest level versus the yen since May 2009. It later pulled back a bit on profit-taking and last stood at 99.25 yen, down 0.1 percent on the day.
The yen's sharp decline, which enhances the competitiveness of Japan's exporters at the expense of their Korean counterparts, dragged shares of top tech-makers lower.
Rising tensions with North Korea added to the pessimism. On Tuesday, North Korean labourers did not report for work at the Kaesong industrial zone it jointly operates with South Korea a day after Pyongyang said it would withdraw workers and suspend operations indefinitely.
Foreigners were net sellers for the fifth day on the Seoul stock market.
Telecoms were leading the losses, with SK Telecom dropping 3.8 percent on worries about earnings.
Techs were in disarray, with chipmaker SK Hynix and LG Display shedding nearly 2 percent while LG Electronics gained 2.43 percent on improving outlook for its smartphones.
Utility Korea Electric Power Corp shed 2 percent, extending the steep losses of the previous two sessions.
Among daily movers, stocks of companies with production in Kaesong fell sharply. Apparel-maker In the F fell 7.9 percent.
Overall, declining shares outnumbered winners 614 to 186.
The KOSPI 200 benchmark of core stocks was down 0.5 percent, while the junior KOSDAQ edged 1.4 percent lower. (Additional reporting by Seongwon Chang; Editing by Sanjeev Miglani)