Collapsed energy giant Enron has chosen Swiss bank UBS AG to take control of its main energy trading business after a hotly contested auction, lawyers for the company said Friday.

Enron chose between Citigroup and UBS in a drawn out auction that took most of this week in New York, but declined to say how much UBS is paying. Company lawyers said they will release details of the winning bid to a New York bankruptcy judge Monday.

"This is a step that will bring back to life the most valuable component of the Enron enterprise," Martin Bienenstock, an attorney for Weil Gotshal & Manges, told U.S. Bankruptcy Court Judge Arthur Gonzalez at a hearing Friday in New York.

Bienenstock asked the judge to set a hearing for Tuesday. The judge must approve the winning bid.

Enron shares have been suspended since the New York Stock Exchange opened Friday, pending news. Shares closed last night at 67 cents, a fraction of their former value of $90 a share 18 months ago.

Citigroup and UBS Warburg have been in the running to buy up to 51 percent of Enron's energy trading unit, which was put up for auction this week after the Houston-based energy trader declared bankruptcy Dec. 2. London based oil company BP (BP.L) said it was also interested in some parts of the unit. 

Negotiators worked late into the night on Thursday to haggle the best possible offer for the trading operations, Enron said.

The move is aimed at restoring market confidence in what was once the world's biggest trader of gas, electricity and other commodities. The operations, dormant since Enron sought Chapter 11 bankruptcy protection Dec. 2, generated most of Enron's $101 billion in revenue in 2000. The company has yet to report its 2001 revenues.

Enron's attempts at revival may be hampered by an expanding barrage of investigations, lawsuits and damaging disclosures that destroyed the energy giant's reputation and ability to transact business and obtain credit. 

On Wednesday, the U.S. Justice Department launched a criminal investigation into the Enron collapse, the latest after others by the Labor Department, the Securities and Exchange Commission and five congressional committees looking to find out whether Enron officials misled investors about its financial condition. 

Enron also faces dozens of civil lawsuits making similar charges of illegal activity on the part of Enron directors. 

These investigations could be hampered by Thursday's jarring disclosure by Arthur Andersen LLP, Enron's auditors, that its staff had disposed of a ``significant but undetermined'' number of documents related to its Enron audits. The accounting firm previously gave the company a clean bill of financial health.

In recent weeks, some creditors filed objections to the trading operation sale, saying it wasn't clear where the proceeds of the business would go when it is revived as expected. 

However, creditors' committee members said they were working to resolve those issues to ensure court approval.

Reuters contributed to this report.