July 25 (Reuters) - Export premiums for corn and soybeans held mostly steady at the U.S. Gulf Coast on Wednesday as demand for each crop was limited by higher futures prices and, in the case of corn, cheaper supplies elsewhere, traders said.
* Tight grain stocks and near record-high prices are keeping a lid on U.S. corn demand while importers turn to cheaper supplies from Brazil and the Black Sea region. Taiwan was said to have bought several corn cargoes from Brazil for shipment in October.
* Soybean demand has also slowed, with top buyer China inquiring about rolling purchases scheduled for autumn shipment to early in 2013 instead, traders said.
* The FOB wheat basis was steady while Morocco's state grains authority ONICL said it may buy up 300,000 tonnes of soft U.S. wheat in a tender next month.
* Traders expected USDA to report disappointing weekly sales in a report due early Thursday.
To check displays of FOB basis, click on following:
U.S. FOB Gulf corn
U.S. FOB Gulf soybeans
U.S. FOB Gulf SRW wheat
U.S. FOB Gulf HRW wheat
* FOB U.S. Gulf Grain
* U.S. grain export summary
* Brazil soybean export prices
* Brazil corn export prices
* Argentine grain prices
* Russian grain prices (Reporting by Michael Hirtzer in Chicago; Editing by Marguerita Choy)