U.S. soybeans inched lower on Friday to put the oilseed on course for its first weekly decline in three weeks, as U.S. harvest supply and a firm dollar offset strong export sales.

Corn edged down as it remained under pressure from brisk harvesting of what is forecast to be a big U.S. crop.

Wheat was up slightly as background weather concerns and talk of U.S. sales to Asia underpinned prices in the face of record global supply.

Chicago Board of Trade November soybeans was down 0.1 percent to $8.97-1/2 a bushel by 1111 GMT as the market stayed below the psychological $9 threshold. The spot contract was down three-quarters of a cent over the week.

"There has been some demand from China and that has supported prices, but on the other hand, supply continues to be very favorable, so traders are weighing up those two currents," said Phin Ziebell, agribusiness economist, National Australia Bank.

An advancing U.S. harvest is adding to large global soybean production, which the U.S. government expects to reach a record high in 2015/16.

Forecasts calling for rain relief in dry Brazilian crop belts eased concerns about soybean planting in the South American exporter.

A firm dollar, reflecting a slide in the euro after the European Central Bank on Thursday hinted at more stimulus measures, also tempered export optimism fueled by a string of sales, mostly to China.

The U.S. Department of Agriculture (USDA) said on Thursday that 463,000 tonnes of U.S. soybeans were sold to unknown destinations, the third such "flash sale" this week.

CBOT December corn fell 0.3 percent to $3.77 a bushel.

Analysts said prices remained under pressure from weak demand for U.S. supplies and the dollar's strength further dampened export prospects.

The USDA said U.S. corn export sales totalled 248,017 tonnes last week, below analyst estimates and the smallest volume so far in the marketing year that started on Sept. 1.

CBOT December wheat gained 0.6 percent to $4.93-1/2 a bushel to steady after falling in the previous session.

Wheat markets remained range-bound as investors weighed up rain forecasts that could help dry growing zones in the United States and the Black Sea region, traders said.

Asian flour millers have stepped up U.S. wheat purchases as dryness in U.S. and Russian wheat belts raised concerns over grain supplies, trade sources said.

The wheat market was also watching for the outcome of an unusually large import tender called by Ethiopia, which is seeking offers on Friday in a tender to buy 1 million tonnes of the cereal.