<PAGE>
Exhibit 23-a Consent of Arthur Andersen, LLP, Independent Accountants
CONSENT OF INDEPENDENT PUBLIC ACCOUNTANTS
As independent public accountants, we hereby consent to the incorporation by
reference in this registration statement of our report dated January 27, 2000
included in KeySpan Corporation's Form 10- K for the year ended December 31,
1999.
/s/ ARTHUR ANDERSEN LLP
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ARTHUR ANDERSEN LLP
August 14, 2000
New York, New York
II-9
<PAGE>
Exhibit 23-b Consent of Ernst & Young, LLP, Independent Auditors
CONSENT OF INDEPENDENT AUDITORS
We consent to the reference to our firm under the caption "Experts" in the
Registration Statement on Form S-3 and the related Prospectus of KeySpan
Corporation for the registration of $1,650,000,000 of debt securities and
to the incorporation by reference therein of our report dated May 22, 1998,
with respect to the financial statements and schedule of Long Island
Lighting Company included in the Annual Report (Form 10-K), as amended, of
KeySpan Corporation (formerly known as MarketSpan Corporation) for the
transition period from April 1, 1998 to December 31, 1998, filed with the
Securities and Exchange Commission.
/S/ ERNST & YOUNG LLP
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ERNST & YOUNG LLP
August 14, 2000
Melville, New York
II-10
