GRAINS-Soybeans set for sixth weekly gain as China steps up purchases

* Soybeans up for 3rd straight day, highest since late May 2018

* China’s robust demand for animal feed supporting prices (Adds quote in paragraph 3, details on fund positioning)

SINGAPORE, Sept 18 (Reuters) - Chicago soybeans were on track on Friday for a sixth weekly gain, climbing to their highest in almost 28 months with support from strong demand in top buyer China.

Corn is poised for a second weekly gain while wheat is in positive territory this week after closing lower last week.

“China’s demand for soybeans is really strong, U.S. beans are still competitive, given the firm crush margins,” said one Singapore-based trader.

The most-active soybean contract on the Chicago Board of Trade was up 1.3% at $10.42-1/4 a bushel, as of 0335 GMT. The market gained more than 4% this week and is on track for more than 20% rally in six weeks.

Corn gained nearly 3% this week and wheat climbed close to 4% this week.

Soybeans led the move higher, fuelled by persistent Chinese demand. The U.S. Department of Agriculture has announced U.S. soy sales to China in each of the past 10 business days, including Thursday’s confirmation of 264,000 tonnes, along with an additional 360,500 tonnes sold to unknown destinations.

China on Thursday set its low tariff rate quota for wheat, corn and rice imports in 2021 at the same volumes as previous years.

The setting of the volumes came as Chinese buyers have been ramping up large volumes of corn imports from the United States, and increased imports of wheat.

High soybean prices are expected to support planting in Argentina this season, but that will be balanced by dry weather, which is driving farmers across the Pampas grains belt to favour late-season corn, which also has attractive prices.

Commodity funds were net buyers of CBOT soybean, corn, wheat and soymeal futures contracts on Thursday and net sellers of soyoil futures, traders said. (Reporting by Naveen Thukral, Editing by Sherry Jacob-Phillips)