CHICAGO, Oct 14 (Reuters) - The government agency that insures corporate pensions has objected to United Airlines' (UALAQ.OB: Quote, Profile, Research) reorganization, asserting in court documents the carrier has changed a deal covering the termination of its pension plans.

The Pension Benefit Guaranty Corp said in a filing late on Thursday the airline's disclosure statement, which details its financial model, is "unconfirmable" as is.

United, a unit of UAL Corp., must get bankruptcy court approval of the disclosure statement before asking creditors to vote on restructuring.

The PBGC complained the reorganization plan is inconsistent with a settlement the parties reached last spring for the airline to turn its underfunded pensions over to the government.

The PBGC said the disclosure statement violates the settlement by restricting its ability to sell securities the government would receive from United in exchange for taking over its four pension plans.

In exchange for taking over UAL's pension, the PBGC was to receive up to $1.5 billion in notes and convertible stock the government would get at United's exit from bankruptcy.

The PBGC said the settlement had placed no restrictions on its ability to sell the securities. But UAL's proposed plan would restrict the transfer of the new equity securities for five years.

"The sale restriction conflicts with the clear and unambiguous terms of the PBGC settlement," the PBGC said.

But a source close to the dispute said the objection on its own would not likely derail United's restructuring.

United spokeswoman Jean Medina said the airline worked closely with its creditors and the PBGC throughout restructuring and would continue to do so.

"We expect to resolve any issues and concerns so that the court can approve our disclosure statement next week and we can continue moving toward exit from bankruptcy," Medina said.

Jeffrey Speicher, a PBGC spokesman, said talks are ongoing. "The PBGC and all other parties are continuing discussions and hope to arrive at an amicable resolution."

But airline consultant Robert Mann said the PBGC's objection could be the first of similar objections that threaten to delay approval of UAL's reorganization plan.

"If they've got concerns then my guess is others will have concerns," Mann said.

United has been in bankruptcy since December 2002. The filing of its reorganization plan and disclosure statement last month marked the beginning of its exit from Chapter 11. United hopes to step out of court protection in early 2006.

United's pension plans covered 120,000 current and retired workers. Jettisoning those accounts, which were underfunded by nearly $10 billion, is a crucial piece of United's restructuring.

The government will insure $6.6 billion of nearly $10 billion in pension plan under-funding at United. Underfunding is the difference between a plan's assets and promised benefits.