(Updates prices, adds comments; changes byline, dateline, previously SYDNEY/PARIS)
CHICAGO, Aug 28 (Reuters) - U.S. wheat and corn futures dropped to life-of-contract lows on Monday, weighed down by technical selling and abundant global supplies, traders and analysts said.
Chicago Board of Trade September wheat futures fell about 2.4 percent, or 9-3/4 cents, to $3.99-3/4 per bushel, in a bear-spreading decline as some investors dumped spot positions ahead of first notice for deliveries against the contract on Thursday.
More actively traded CBOT December wheat eased 7-3/4 cents to $4.27-1/2 per bushel.
"For the wheat market, once again the path of least resistance is lower," said EFG Group analyst Tom Fritz. "Last week, we tried to get a reversal on the idea the market was oversold and it fizzled."
Wheat prices also eased in Russian cash markets, under pressure from a large crop.
CBOT December corn hit a contract low of $3.50-1/2 per bushel before trimming losses to $3.51-1/4, down $2-1/4 cents at 12:54 p.m. CDT (1754 GMT).
CBOT November soybeans declined 1-1/2 cents to $9.43 per bushel, following losses in grain prices ahead of the harvest of an expected record-large U.S. soy crop.
U.S. Commodity Futures Trading Commission data on Friday showed speculative investors increased their net short, or bearish, positions in wheat, corn and soy.
Advisory service Pro Farmer last week predicted bumper U.S. soy and corn harvests that will begin hitting markets in the next several weeks.
The forecast by Pro Farmer added to a bearish tone in the wake of the U.S. Department of Agriculture's forecast on Aug. 10 for bigger-than-expected harvests.
Analysts surveyed by Reuters expected the USDA after the close of trading to increase good-to-excellent condition ratings for the U.S. corn crop and leave soy ratings unchanged. (Reporting by Michael Hirtzer; Additional reporting by Colin Packham in Sydney and Sybille de La Hamaide in Paris)