* KOSPI falls, foreigners net sellers

* Korean won weakens against U.S. dollar

* South Korea benchmark bond yield falls

* For the midday report, please click

SEOUL, March 23 (Reuters) - Round-up of South Korean financial markets:

** South Korean shares ended lower for a third straight session on Tuesday, as investors awaited fresh comments from top U.S. policymakers and the U.S. Treasury auctions. Both the won and the benchmark bond yield fell.

** The KOSPI ended down 30.72 points, or 1.01%, at 3,004.74, its lowest closing since March 11. It ended 0.13% lower on Monday.

** Chip giants Samsung Electronics and SK Hynix fell 0.24% and 2.17% each, towing benchmark declines, while battery maker LG Chem and internet giant Naver tumbled 3.73% and 2.65%, respectively.

** The 10-year U.S. bond yields eased to 1.684% after peaking at 1.754% on Thursday, but market's immediate focus is on the Congressional testimony by Federal Reserve Chair Jerome Powell and Treasury Secretary Janet Yellen later in the day.

** Demand for U.S. Treasuries will be tested this week as $183 billion of notes are due to be auctioned, with one seven-year note sale likely to be closely watched after an auction of that maturity stumbled last month.

** "Eyes are on sales of two-year notes later in the day ... and remarks from Fed officials over bond yields and inflation," said Kiwoom Securities' analyst Seo Sang-young.

** Foreigners were net sellers of 477.6 billion won ($423.09 million) worth of shares on the main board.

** The won ended at 1,129.7 per dollar on the onshore settlement platform, 0.12% lower than its previous close at 1,128.4.

** In offshore trading, the won was quoted at 1,128.8, while in non-deliverable forward trading its one-month contract was quoted at 1,128.9.

** The most liquid 3-year Korean treasury bond yield fell by 0.1 basis points to 1.129%, while the benchmark 10-year yield fell by 2.7 basis points to 2.031%.

($1 = 1,128.8300 won) (Reporting by Joori Roh; Editing by Rashmi Aich)