Oct 15 (Reuters) -ICE cotton futures slipped on Tuesday and hovered near three-week lows hit in the previous session, as downbeat sentiment in grains and crude oil markets pressured prices.

* Cotton contracts for December CTZ4 fell 0.2 cent, or 0.2%, to 70.89 cents per lb at 11:45 a.m. ET (1545 GMT). The contract hit its lowest level since Sept. 18 on Monday.

* "There's a meltdown going on in the Chicago markets. Corn and soybeans have lost a lot of price in the last two weeks due to good weather in Brazil, so that's really weighing on cotton," said Rogers Varner, president of Varner Brokerage in Cleveland.

* Chicago corn and soybean futures fell for a fourth straight session to multi-week lows as the prospect of bumper U.S. harvests and timely rain for planting in Brazil kept the focus on ample global supply. GRA/

* "The dollar's been strong recently. It's not so much strong today, but it's been very strong over a three-week period. So these factors are pushing cotton down," Varner added.

* The U.S. dollar eased slightly, but was still near its highest in more than two months, making cotton more expensive for holders of other currencies. USD/

* Meanwhile, oil prices tumbled more than 4% to a near two-week low due to a weaker demand outlook and easing fears of a supply disruption. O/R

* Lower oil prices make cotton-substitute polyester less expensive.

* "There's some demand (for cotton) at around $0.70, the market has stopped there temporarily. It's also about four cents cheaper than it was a few weeks ago, so I do think there will be some better demand at $0.70," Varner said.

* Traders await the weekly export sales report from the U.S. Department of Agriculture (USDA) due on Thursday.

Reporting by Anjana Anil in Bengaluru; Editing by Maju Samuel