* Most-active CBOT corn ends above $7 a bushel

* China cancels pricey U.S. corn purchases - USDA

* Mexico, unknown buyers strike deals for U.S. corn

* Soybean, wheat futures also finish higher

CHICAGO, May 5 (Reuters) - Chicago Board of Trade corn futures touched their highest price in more than eight years on Wednesday as concerns over global supplies and strong demand continued to fuel strong gains.

A blistering rally in the market has raised costs for global producers of corn-based ethanol and of meat made from livestock that consume the grain as feed.

The December contract, which represents the U.S. crop that will be harvested this autumn, posted the biggest gains in the latest surge.

The market is on a "mission to capture more acres" by using high prices to entice farmers to increase corn plantings, said Rich Feltes, head of market insights for broker RJ O'Brien.

The most-active corn contract settled up 11-3/4 cents at $7.08-1/2 per bushel. It earlier reached $7.12, its highest price since March 2013.

December corn finished up 24-1/4 cents at $6.04-3/4 a bushel and set a contract high of $6.06-1/2.

CBOT wheat ended up 17-3/4 cents at $7.44-1/2 per bushel, boosted by the gains in corn.

Most-active soybeans settled up 4 cents at $15.42-1/4 per bushel. November soybeans, which represent the crop that will be harvested in the autumn, soared 19-1/2 cents to $13.82-3/4 a bushel.

An uptick in crop prices began last year as China accelerated imports of U.S. crops, tightening supplies.

China cancelled purchases of 140,000 tonnes of U.S. corn for delivery in the 2020/2021 marketing year, following the recent surge in prices, the U.S. Department of Agriculture said.

Yet, the USDA also reported that exporters sold 184,100 tonnes of U.S. corn to Mexico and a total of 147,320 tonnes to unknown buyers.

In Brazil, a rival corn producer and exporter, dry weather continues to raise crop concerns.

Brazil's cereal exporter association Anec said the country would ship some 32 million tonnes of corn this year, 1.6 million tonnes less than in 2020. (Reporting by Tom Polansek in Chicago, Sybille de la Hamaide in Paris and Naveen Thukral in Singapore; Editing by Rashmi Aich, Chizu Nomiyama, Barbara Lewis and David Gregorio)