* Corn futures fall 0.8%, give up some of last session's gains
* Wheat dips, losses limited by firm demand, rising world prices (Adds details, quote in paragraphs 5,6)
SINGAPORE, Jan 21 (Reuters) - Chicago corn slid nearly 1% on Tuesday, easing after notching its biggest one-day gain in more than three months in the previous session with Chinese demand likely to provide a direction to the market.
Wheat prices lost ground although losses were curbed by strong global demand and rising prices in rival exporting countries.
The most-active corn contract on the Chicago Board of Trade was down 0.8% to $3.86 a bushel by 0308 GMT, having gained 3.7% on Friday, the biggest one-day gain since Oct. 11.
Wheat was down 0.3% to $5.68-3/4 a bushel, having closed up 0.9% on Friday. Soybeans lost 0.4% to $9.26 a bushel, having firmed 0.6% in the last session.
"There were rumours in the market on Friday that Chinese buyers were looking to book U.S. cargoes but U.S. grain elevators have yet to confirm any Chinese buying," said one Singapore-based grains trader.
"I think the market is waiting for Chinese buying."
U.S. markets were closed on Monday due to a public holiday. China committed to increase purchases of U.S. farm products by $32 billion over two years, including $12.5 billion above the corresponding 2017 baseline of $24 billion in 2020 and $19.5 billion above the baseline in 2021.
However, China's pledge to buy U.S. agricultural goods based on "market conditions" added to doubts about the size of any future purchases.
The U.S. Department of Agriculture (USDA) reported export sales of U.S. 2019/20 corn in the week ended Jan. 9 at 784,700 tonnes and 2019/20 wheat at 650,600 tonnes, topping trade expectations.
Weekly soybean sales were in line with expectations at 711,400 tonnes.
Large speculators increased their net short position in CBOT corn futures in the week to Jan. 14, regulatory data released on Friday showed.
The Commodity Futures Trading Commission's weekly commitments of traders report also showed that noncommercial traders, a category that includes hedge funds, switched to a net long position in CBOT wheat and trimmed their net short position in soybeans.
The U.S. wheat market has been supported by robust demand and rising prices in the Black Sea region.
Pakistan on Monday approved the import of 300,000 tonnes of wheat to relieve a shortage of flour supplies that has created a crisis for the government of Prime Minister Imran Khan.
(Reporting by Naveen Thukral; Editing by Subhranshu Sahu)