March 24 (Reuters) - ICE cotton futures crawled higher on Friday, supported by mill fixations, but were down 1 percent for the week.

"The market is supported by the need for mills to fix on-call sales," said Louis Rose, an independent cotton trader and consultant with Risk Analytics in Memphis.

However, cautious speculators prevented the market from surging ahead of the index fund roll periods and USDA prospective planting report, Rose added. The U.S. Department of Agriculture prospective planting report is scheduled for release on March 31.

The May cotton contract on ICE Futures U.S. was down 1 percent for the week, in the biggest weekly decline since the seven-day period ending Feb. 17.

Speculators cut their net long position in cotton by 4,319 contracts to 109,050 in the week to March 21, U.S. Commodity Futures Trading Commission data showed on Friday.

* The May cotton contract on ICE Futures U.S. settled up 0.2 cent, or 0.26 percent, at 77.47 cents per lb. It traded within a range of 77.17 and 78.15 cents a lb.
* Total futures market volume rose by 6,927 to 26,085 lots. Data showed total open interest gained 1,609 to 281,312 contracts in the previous session.
* The dollar index was down 0.11 percent.

(Reporting by Karen Rodrigues in Bengaluru; Editing by Leslie Adler)