UPDATE 2-Huntsman withdraws Tronox motion

* Huntsman withdraws motion for Tronox auction-documents

* No reason given for Huntsman change

* Huntsman likely to receive break-up fee, expenses

(Adds market activity, attempt to reach Huntsman)

NEW YORK, Dec 22 (Reuters) - Huntsman Corp (HUN.N) has withdrawn its request that a bankruptcy court force Tronox Inc to go ahead with an auction for its assets even though the bankrupt U.S. chemicals maker had said it planned to pursue an alternate plan, according to court documents.

Tronox TRXAQ.PK had been scheduled to hold an auction on Dec. 21 for its titanium dioxide plants in the Netherlands and the United States, and a 50 percent joint venture interest in a titanium dioxide plant in Australia and electrolytic production facilities.

Rival chemical maker Huntsman, which said it would bid $415 million for the assets, had been scheduled to be the lead bidder, or "stalking horse," at the auction.

But on Tuesday, Huntsman filed documents with the court saying the company was withdrawing its motion for an order directing Tronox to comply with the bidding procedures. A company spokesman was not immediately available to say why Huntsman withdrew the motion.

Huntsman likely will receive a break-up fee and expense reimbursement. The amount of those possible fees was not immediately known.

Tronox has said in court documents that it intends to pay Huntsman those amounts.

Huntsman stock was 7 cents higher at $11.25 in afternoon trading on the New York Stock Exchange.

The case is: In re: Tronox Inc, U.S. Bankruptcy Court, Southern District of New York, No. 09-10156.

(Reporting by Chelsea Emery. Editing by Robert MacMillan)