CHICAGO: Chicago Board of Trade corn futures rebounded from prior-session losses on Wednesday, supported by good export demand and positioning ahead of a monthly US government crop report due on Thursday, traders said.

Gains were limited by improving crop weather in South America, with rains expected in parts of Brazil and northern Argentina.

CBOT most-active March corn rose 4 cents to $4.23-3/4 cents per bushel.

Traders are looking ahead to Thursday's US Department of Agriculture (USDA) monthly supply-and-demand report, which is expected to show tighter US and global stocks and smaller crops in Argentina and Brazil.

Robust export demand underpinned corn. The USDA on Wednesday confirmed private sales of 257,071 tonnes of US corn to Mexico, the latest is a series of large purchases by major importers.

The USDA is due to issue weekly export sales data early on Thursday. Analysts expect net US corn sales between 700,000 and 1.5 million tonnes.

The US Energy Information Administration said ethanol production rise by 17,000 barrels per day last week and stocks of the biofuel rose.