"It is unfortunate that we have been forced to sue to enforceour rights," World Trade Center developer and leaseholder LarrySilverstein says. "We are confident of our legal position thatcrashes of two separate planes into two separate towers at twoseparate times entitle us to claim that there was more than oneoccurrence within the meaning of our insurance contracts."

A spokeswoman from Travelers said the company has not yet seenthe lawsuit and therefore would not comment. Travelers, Swiss Reand more than 20 other companies insured the World Trade Center ina $3.6-billion "per occurrence" policy. Swiss Re filed suit againstWTC developer Silverstein in October, claiming the Sept. 11bombings constituted a single occurrence. Silverstein countersuedshortly thereafter.

Silverstein's attorneys now say they plan to ask the court forpermission to amend their counterclaim in the Swiss Re suit toinclude as defendants nearly all of the more than 20 WTC insurersfollowing a breakdown in settlement negotiations. Excluded from theamended list are insurers ACE Bermuda and XL.