Exhibit 99.A

April 18, 2006

Securities and Exchange Commission

100 F Street, N.E.

Washington, D.C. 20549

Commissioners:

We have read the statements made by El Paso Natural Gas Company (copy attached), which we understand will be filed with the Securities and Exchange Commission, pursuant to Item 4.01 of Form 8-K, as part of the Form 8-K of El Paso Natural Gas Company dated April 12, 2006. We agree with the statements concerning our Firm in such Form 8-K.

Very truly yours,

/s/ PricewaterhouseCoopers LLP

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