June 8 (Reuters) -Basis bids for corn shipped by barge to U.S. Gulf Coast terminals were narrowly mixed on Thursday on tight nearby supplies and sluggish export demand, traders said.

* CIF soybean basis bids were flat to lower, although spot bids remained at a sizeable premium to deferred-month loadings due to snug supplies in the export pipeline.

* Slow U.S. corn and soybean export demand anchored export premiums at the Gulf. Cheaper Brazilian supplies are undercutting demand.

* Three South Korean importers made large corn purchases on Thursday, and traders said the grain would likely be sourced from South America. GRA/TEND

* U.S. corn export sales last week totaled a net 65,926 metric tons for the current and next marketing years, according to U.S. Department of Agriculture (USDA) data. It was the latest in a series of sub par sales weeks for U.S. corn.

* Soybean export sales totaled 471,876 metric tons for the combined marketing years, down slightly from a week earlier, USDA data showed.

* CIF corn barges loaded in the first half of June were bid 2 cents higher, at 77 cents, over CBOT July CN3 futures. Bids for more immediate loadings and afloat barges were at least 3 cents above that. Full-month June loadings were bid steady at 65 cents over futures.

* FOB corn export premiums for loadings in late June were around 85 cents over July CN3 futures and early July loadings were offered 73 cents over futures, steady.

* Soybean barge basis bids for first-half June loadings were down 7 cents at 88 cents over CBOT July SN3 futures after trading as high as 95 cents over futures earlier in the week. Full-June bids were also 7 cents lower at 70 cents over futures.

* FOB soybean premiums for late June loadings held steady at 95 cents over futures.

Reporting by Karl Plume in Chicago

For displays of CIF basis, click on the codes in brackets: U.S. CIF Gulf soybeans GRYM U.S. CIF Gulf corn GRYN U.S. CIF Gulf SRW wheat GRYO U.S. CIF Gulf HRW wheat GRYP For displays of FOB basis, please click on the following codes in brackets: U.S. FOB Gulf corn GRZC U.S. FOB Gulf soybeans GRZD U.S. FOB Gulf SRW wheat GRZE U.S. FOB Gulf HRW wheat GRZF LINKS Corn prices page: cpurl://apps.cp./cms/?pageid=corn-cash-market
Wheat prices page: cpurl://apps.cp./cms/?pageid=wheat-cash-market
U.S. barge freight BG/US
U.S. export sales estimates USDA/EST U.S. grain export summary GRA/U Brazil soybean export prices SYBS Brazil corn export prices SYBX Argentina grain prices GRA/ARG Russia grain prices GRA/RU