NEW YORK (Reuters) - Regional phone company XO Communications Inc. yesterday sweetened its bid to acquire Bermuda-based Global Crossing Ltd. and said it is willing to bid for either the debt or the assets to take control of the bankrupt high-speed communications network operator.

Singapore Technologies Telemedia already has an agreement to pay $250 million for a 61.5-percent stake in Global Crossing, which filed for bankruptcy protection in January 2002 under a massive debt load, a glut of high-speed network capacity, and slim demand.

XO, controlled by billionaire investor Carl Icahn, on May 30 offered more than $700 million for Global Crossing, or $250 million in cash and the rest in debt, stock and warrants.

Today, Icahn, who controls more than 80 percent of XO's stock, said he would offer more $700 million wholly in cash for Global Crossings assets, which includes a high-speed network reaching 27 countries.

Alternatively, he said he would offer to buy any or all of its bank debt at $210 per $1,000 at face value, or a total of $472.5 million for its $2.25 billion in face value of debt.

Global Crossing, which faces an accounting probe by the Securities and Exchange Commission and other governmental authorities, did not immediately return calls seeking comment.

Icahn, who took control of XO in January when it emerged from Chapter 11 bankruptcy, said the Global Crossing board continues to "ignore our bona fide purchase offer," which would be contingent on the cancelling of the Singapore Technologies deal.

The bankruptcy court must rule on the deal with Singapore Technologies before any new bids for Global Crossing can be considered. Telephone company IDT Corp. also has said it would bid for Global Crossing.

Singapore Technologies became the sole investor slated to gain control of Global Crossing after Hutchison Whampoa Ltd. walked away from the deal in April.

US national security officials balked at Hong Kong-based Hutchison's ties to China, and some analysts have said the Singapore Technologies deal still may spark objections from US lawmakers. The company is a unit of Temasek Holdings Ltd., the investment arm of the Singapore government.

"Hopefully, this $700 million cash offer and the 'any and all' tender will put to rest any questions about the seriousness of the XO offer," said Icahn in an interview. "I hope this will serve to expedite this process and maintain the value of these assets."

Icahn said his latest offer would eliminate national security concerns and also eliminate risk to banks and creditors if the Singapore deal didn't go through.