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,   as  amended  (Registration  No.
333-53657)   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
ARTHUR ANDERSEN LLP


New York, New York
December 11, 2000




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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
Post-Effective  Amendment  No. 1 to the  Registration  Statement  (Form  S-3 No.
333-53657) of KeySpan  Corporation 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) of KeySpan Corporation (formerly known as MarketSpan  Corporation) for the
year ended December 31, 1999, as amended, filed with the Securities and Exchange
Commission.


/S/ ERNST & YOUNG LLP
ERNST & YOUNG LLP

December 13, 2000
Melville, New York

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