Aug 29 (Reuters) - ICE cotton futures edged up on Thursday, gaining for a third straight session, as positive sentiment around U.S.-China trade talks supported prices even as federal data showed export sales declined again last week. * Cotton contracts for December settled up 0.27 cent, or 0.46 %, at 59 cents per lb as of 3:10 p.m. EDT (1911 GMT). It traded within a range of 57.94 and 59.29 cents a lb.

* "The headlines on the U.S.-China trade war are definitely not having a negative effect on the prices today," said Jim Nunn, owner of Tennessee cotton brokerage Nunn Cotton, adding the market has been very volatile.

* China struck a hopeful tone on trade relations with the United States as Beijing and Washington were discussing the next round of face-to-face talks scheduled for September.

* Prices had fallen to 3-1/2 years on Monday and have declined nearly 20% so far this year as the U.S.-China trade war hurt demand of the natural fiber. Cotton prices are also on track to post their fifth straight month of falls.

* Meanwhile, weekly data from the Unites States Department of Agriculture (USDA) showed net sales of 146,000 running bales, down nearly 11% from what was reported the previous week.

* "The export sales were below mediocre. Hurricane Dorian is going to be more or less neutral. Pretty good rains in west Texas this week will help the crop," said Rogers Varner, president of Varner Brokerage in Cleveland, Mississippi.

* Rains in Texas, a major crop-producing state, is helping the crop previously hit by extreme heat.

* The USDA's weekly crop progress report on Monday rated 43% of U.S. cotton in good-to-excellent condition, down 6 percentage points from a week ago.

* Total futures market volume fell by 1,369 to 16,810 lots. Data showed total open interest gained 1,887 to 221,262 contracts in the previous session. (Reporting by Diptendu Lahiri in Bengaluru; Editing by Lisa Shumaker)