S.Korea shares fall on U.S. yield spike, China policy tightening woes

* KOSPI falls, foreigners net sellers

* Korean won weakens against U.S. dollar

* South Korea benchmark bond yield rises

* For the midday report, please click

SEOUL, Feb 22 (Reuters) - Round-up of South Korean financial markets:

** South Korean shares ended lower on Monday, reversing early gains, as strong local exports data were offset by a spike in U.S. Treasury yields and concerns about policy tightening in China. The won weakened, while the benchmark bond yield rose.

** The benchmark KOSPI closed down 27.87 points, or 0.90%, at 3,079.75, after rising as much as 1.12% in early trade.

** Most heavyweights slid, with chip giant Samsung Electronics down 0.48%, while internet giant Naver and LG Chem tumbled 2.89% and 2.66%, respectively. Samsung’s peer SK Hynix, however, rose 2.63%.

** South Korea’s exports during the first 20 days of February expanded 16.7% from a year earlier, data showed on Monday, faster than a 10.5% rise during the Jan. 1-20 period, thanks to a sales boost in major products and strong global demand.

** U.S. 10-year Treasury yields spiked on expectations that massive government stimulus would lead to higher growth and inflation, while there are mounting speculation that the Chinese authorities may begin to adopt a tighter policy stance.

** The Bank of Korea is expected to keep interest rates at a record low on Thursday, as a sluggish labour market keeps policymakers under pressure.

** Foreigners turned net sellers of 315.9 billion won ($284.71 million) worth of shares on the main board.

** The won ended at 1,110.4 per dollar on the onshore settlement platform, 0.41% lower than its previous close at 1,105.9.

** In offshore trading, the won was quoted at 1,109.4, while in non-deliverable forward trading its one-month contract was quoted at 1,109.2.

** In money and debt markets, March futures on three-year treasury bonds fell 0.09 points to 111.48.

** The most liquid 3-year Korean treasury bond yield rose by 2.3 basis points to 1.020%. ($1 = 1,109.5400 won) (Reporting by Joori Roh; Editing by Rashmi Aich)