(Updates to mid-morning)
* Upbeat revision of U.S. Q3 growth provides support
* Credit squeeze in China and weak yen weigh
* Hyundai Group shares rally
By Christine Kim
SEOUL, Dec 23 (Reuters) - Seoul shares rose to their highest in nearly two weeks on Monday morning, as sentiment was underpinned by an upward revision in third-quarter U.S. growth data over the weekend.
The Korea Composite Stock Price Index (KOSPI) was up 0.7 percent at 1,996.77 points by 0150 GMT, and also touched its highest since Dec. 11 shortly after markets opened.
Revised data showed U.S. gross domestic product grew at a 4.1 percent annual rate instead of 3.6 percent, marking the fastest growth in nearly two years during the July-September period. A sustained recovery in the world's largest economy supported sentiment in local stocks.
However, anxiety over a credit crunch in China, kept investors wary after the Chinese central bank said it had added $50 billion in three days to the interbank market last week.
A sharply depreciating yen also turned investors wary after the Japanese currency hit a more than 5-year low against the won last week, weighing on the competitiveness of local exporters against their Japanese rivals.
"The situation is expected to improve in time. There aren't many issues that can suddenly emerge as negative factors and expectations for the U.S. economy are improving after the Federal Reserve announced it would taper its stimulus," said Han Beom-ho, a senior analyst at Shinhan Investment Corp in Seoul.
Shares in shipping line Hyundai Merchant Marine and Hyundai Elevator rose by their daily limit of 15 percent on Monday.
The rallies followed news on Sunday that Hyundai Group planned to raise more than 3.3 trillion won ($3.11 billion) by selling three financial units including Hyundai Securities to ease concerns on affiliates' high debt levels.
Hyundai Group was split in ownership from carmaker Hyundai Motor Group and shipbuilder Hyundai Heavy Group between 1999 and 2000.
Foreigners and institutions were net buyers, with offshore investors purchasing 69 billion won ($65.02 million) worth of KOSPI shares near the mid-session, buttressing the index.
Advancing shares outnumbered losers 432 to 325.
The KOSPI 200 benchmark of core stocks was up 0.8 percent, while the junior KOSDAQ rose half a percent.
($1 = 1061.2000 Korean won) (Additional reporting by Joyce Lee and Seongwon Chang; Editing by Jacqueline Wong)