* USDA expected to raise U.S. corn crop forecast

* Soybeans firm, wheat flat

HAMBURG, July 12 (Reuters) - U.S. corn futures rose on Monday following heavy falls last week as traders readied for a closely-watched world supply and demand report from the U.S. Department of Agriculture (USDA) due later on Monday.

Forecasts of hotter U.S. weather also supported corn. Soybeans were firm and wheat was little changed.

Chicago Board of Trade's most active corn contract rose 0.9% to $5.22 a bushel at 1044 GMT, having fallen 12% last week as rain and moderate temperatures were seen as beneficial for corn crops in the U.S. Midwest.

Soybeans rose 0.1% to $13.31 a bushel, wheat was flat at $6.15 a bushel.

The USDA's world supply and demand report scheduled at 1600 GMT on Monday is expected to forecast an increased U.S. corn harvest but a smaller U.S soybean crop.

Estimates of smaller U.S. corn and soybean inventories are also expected from the USDA.

"People are squaring away ahead of the USDA report," said Phin Ziebell, agribusiness economist at National Australia Bank. "People are looking for direction and the USDA will provide that."

Traders also noted strong Asian import demand for corn, with three South Korean groups issuing separate corn import tenders on Monday.

"Import demand for corn is visible today," one European trader said. "But the USDA reports so often provide fireworks and the USDA is firmly in the centre of attention."

"Corn is also receiving support from forecasts of hotter U.S. Midwest weather."

Soybeans drew support from demand for U.S. exports, including recent sales to Mexico.

Saudi Arabia bought a hefty 505,000 tonnes of wheat in an international tender on Monday at an average price of $287.00 a tonne c&f. This was sharply down from the $299.55 average price paid in its previous tender in May. (Reporting by Michael Hogan in Hamburg and Colin Packham in Canberra, editing by David Evans)