Jan. 27 (Bloomberg) -- Lyondell Chemical, the bankrupt chemical maker, has asked a judge to bar one of its largest creditors, BASF Corp., from seeking a claim of $200 million it says is “null and void.”

Lyondell asked U.S. Bankruptcy Judge Robert Gerber to stop BASF from litigating its claim to an appeal bond of $200 million. Lyondell took out the bond in 2007 to appeal a ruling ordering it to pay $169.9 million plus interest to BASF. Lyondell said the appeal bond was declared “null and void” when a New Jersey court dismissed Lyondell’s appeal on Jan. 16. BASF has asked to vacate the dismissal and reinstate the bond.

“These acts each violated the automatic stay,” Lyondell said in court documents. Under bankruptcy law, an automatic stay protects companies from lawsuits while they reorganize.

The lawsuit being appealed dates to 2005, when BASF sued Lyondell for breach of contract as the two chemical makers disputed the price at which Lyondell was to convert BASF’s propylene to another chemical agent. Their deal had called for a “most-favored-nation” price.

Following BASF’s request to reinstate the bond, Judge Christine Miniman of the New Jersey Appellate Division on Jan. 22 issued an order temporarily reinstating it, requiring Lyondell to maintain the appeal bond.

Lyondell, which filed for bankruptcy Jan. 6 citing waning demand for its products, said in its initial petition for bankruptcy that BASF may have a claim of $206.4 million under a judgment which is “contingent and disputed.” BASF, based in Florham Park, New Jersey, is a unit of BASF SE, the world’s largest chemical producer, based in Ludwigshafen, Germany.

The case is In re Lyondell Chemical Co., 09-10023, U.S. Bankruptcy Court, Southern District of New York (Manhattan).

To contact the reporter on this story: Tiffany Kary in New York Bankruptcy Court at tkary@bloomberg.net.

Last Updated: January 27, 2009 11:02 EST