* KOSPI rises, foreigners net sellers * Korean won strengthens against U.S. dollar * South Korea benchmark bond yield rises SEOUL, June 1 (Reuters) - Round-up of South Korean financial markets: ** South Korean shares extended gains on Tuesday, as investors lapped up stellar exports data and factory activity, which implied stronger growth for Asia's fourth-largest economy. The Korean won strengthened, while the benchmark bond yield rose. ** The benchmark KOSPI was up 22.82 points, or 0.71%, at 3,226.74, as of 0207 GMT. ** South Korean exports logged their sharpest expansion in 32 years in May, marking another robust month of shipments, fuelled by stronger consumer demand globally as many economies start to reopen. ** The country's factory activity in May also extended growth into an eighth straight month, a private sector survey showed on Tuesday, due to recovery in global demand although the pace of expansion eased slightly. ** Among the heavyweights, technology giant Samsung Electronics rose 0.37% and peer SK Hynix climbed 1.18%, while LG Chem rose 1.10% and Naver advanced 1.52%. ** Foreigners were net sellers of 86.7 billion won worth of shares on the main board. ** The won was quoted at 1,106.4 per dollar on the onshore settlement platform , 0.41% higher than its previous close at 1,110.9. ** In offshore trading, the won was quoted at 1,105.8 per dollar, up 0.1% from the previous day, while in non-deliverable forward trading its one-month contract was quoted at 1,105.1. ** The trading volume during the session in the KOSPI index was 589.47 million shares. Of the total traded issues of 912, the number of advancing shares was 533. ** The won weakened 1.8% against the dollar so far this year. ** In money and debt markets, June futures on three-year treasury bonds rose 0.02 points to 110.74. ** The most liquid 3-year Korean treasury bond yield fell by 0.9 basis points to 1.219%, while the benchmark 10-year yield rose by 0.9 basis points to 2.188%. (Reporting by Cynthia Kim; Additional reporting by Jihoon Lee, Editing by Sherry Jacob-Phillips)