GRAINS-Wheat falls to three-week low, corn and soy prices climb

* Corn, soy prices boosted by U.S. crop concerns

* Global wheat stocks seen rising to record level (Adds quotes, updates prices)

LONDON, July 20 (Reuters) - U.S. wheat futures hit a three-week low on Thursday, weighed down by ample global supplies, while corn and soybean prices were higher, buoyed by continued fears of further crop damage.

The most active wheat futures on the Chicago Board Of Trade were down 0.55 percent at $5.00-1/4 a bushel by 1017 GMT after touching a low of $4.95 - the weakest since June 29.

Prices had risen in late June and early July, boosted partly by diminishing prospects for the U.S. spring wheat crop, but dealers said the focus had begun to shift back to the overall abundance of wheat supplies around the world.

"After a number of sizeable supply surpluses in succession, global stocks find themselves at a record level. This is also unlikely to change in 2017/18," Commerzbank said in market note.

The U.S. Department of Agriculture (USDA) last week forecast that global wheat stocks would climb to a record level at the end of the 2017/18 season despite the U.S. spring wheat crop falling to a 15-year low.

"The USDA report last week has reminded everyone that there is a lot of wheat in the world," said Angus Thornton, commodity analyst at Profarmer.

Milling wheat futures on Euronext were also lower, with December down 0.4 percent at 177.50 euros a tonne.

Dealers said the wheat harvest in top EU producer France had advanced into the north of the country and production was set to rebound from last year's sub-par levels.

"Harvest progress is adding pressure on grain prices while qualities and volumes are reassuring buyers that were not active up until now," analysts Agritel said.

Corn and soybean futures extended recent gains, boosted by concerns that mostly dry weather could curb production in the U.S. Midwest.

The most active CBOT corn futures rose 0.8 percent to $3.99-1/2 a bushel.

The recent dry weather has already dented crop quality.

Corn crop condition ratings declined earlier this week in top-producing states of Iowa, Illinois and Nebraska, and extended outlooks for limited rainfall were seen as threatening to corn plants during their yield-setting pollination phase.

"Both corn and soybean crops are now in significantly worse condition than at the same point last year, as well as below the average for the past 28 years," Commerzbank said.

The most active soybean futures rose 0.8 percent to $10.20-1/4 a bushel.

The USDA will release weekly U.S. grain and soy export sales later on Thursday that will show whether global importers bought U.S. supplies during a volatile week of futures trading last week. Analysts said the data will help determine the trend for the rest of the session. (Additional reporting by Colin Packham; Editing by Richard Pullin and David Evans)