CHICAGO, Jan 29 (Reuters) - Spot basis bids for soybeans and corn were mixed in the U.S. Midwest on Wednesday, following a week of increased farmer sales, and as Chicago Board of Trade corn and soybean futures rose.

* The soy basis fell at an Ohio elevator, an Illinois River terminal and an Iowa processor. The basis rose at an Ohio river terminal.

* The corn basis rose at an Ohio river terminal and an Indiana ethanol plant, but fell at another ethanol plant in Iowa.

* The basis weakened in some areas because buyers had already purchased enough grain and oilseeds for their short-term needs, according to analysts.

* U.S. corn and soybean futures rose on Wednesday on expectations of tighter corn supplies, a drier long-term forecast in Argentina and a harvest slowed by rains in parts of Brazil, analysts said.

* Most-active CBOT corn futures Cv1 were up 9-1/4 cents at 11:30 a.m. CST (1730 GMT) to $4.94-1/2 a bushel, while most-active soy futures Sv1 were last up 13-1/4 cents to $10.58-1/4 a bushel.

Basis values are quoted against CBOT futures in cts/bu:

NOTE: 0 = Option price, UNC = Unchanged, UNQ = Unquoted

NC = Not comparable, DP = Delayed price, N/A = Not available,

F = January, H = March, K = May, N = JulyQ = August, U = September, X = November, Z = December

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LINKS: 0#USCSHGRN-PM

For U.S. forward basis spreadsheets, please click:

CORN/BASIS, SOYA/BASIS, WHEAT/BASIS, MILO/BASIS

- CBOT corn report COR/

- CBOT soybean report SOY/C

- CBOT wheat report WHE/C

- U.S. grain barge freight values BG/US

- U.S. Midwest cash grain PM GRA/PM

- U.S. CIF/FOB Gulf Grain GRA/F

(Reporting by Renee Hickman; Editing by Vijay Kishore)

((renee.hickman@thomsonreuters.com))