* SK Hynix beats Q1 forecasts
* STX units soar on cash injection hopes
* Hyundai Hysco up 14.8 pct on Q2 outlook
* Foreigners sell for ninth session
By Somang Yang
SEOUL, April 24 (Reuters) - South Korean shares climbed on Wednesday on better-than-expected results from tech heavyweights including chipmaker SK Hynix but dealers said gains were likely to be limited because of concerns that a weaker yen would hurt firms' competitiveness.
The Korea Composite Stock Price Index (KOSPI) rose 0.9 percent to close at 1,935.31 points, the highest close since Apr. 11.
"In contrast to last week, when weak earnings from industrials depressed the index, today's tech results are giving the market a boost," said Kim Hyung-ryul, an analyst at Kyobo Securities.
However, Kim said that the rebound from earnings was likely to be temporary, as Asia's fourth largest economy faces headwinds from a weaker yen which gives Japanese rivals an advantage.
Chipmaker SK Hynix Inc shares closed 0.9 percent higher after posting forecast-beating operating profits for the Jan-March period.
LG Electronics, closed down 0.4 percent after its quarterly profit fell 13 percent because of razor-thin margins for its TV division.
The KOSPI's gains widened near mid-session as five affiliates of STX Offshore & Shipbuilding Co Ltd jumped nearly 15 percent on media reports that a Korea Development Bank (KDB)-led restructuring programme will kick off this week, raising hopes for a cash injection to the troubled group.
Hyundai Hysco, an automotive steel supplier for Hyundai Motor, also leapt 14.8 percent after a brokerage forecast a rise in April-June profits.
Overall, 630 advancing shares outnumbered 195 decliners.
Buying by local institutions insulated the main board as foreigners sold for the ninth day.
The KOSPI 200 benchmark of core stocks was up 0.8 percent, while the junior KOSDAQ climbed 1.7 percent.
Move on day +0.87 percent
12-month high 2,031.10 2 January 2013
12-month low 1,769.31 25 July 2012
Change on yr -3.09 percent
All-time high 2,231.47 27 April 2011
All-time low 93.10 6 January 1981 (Editing by Sanjeev Miglani)