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Exhibit 99.1

I, Jeroen van der Veer, certify
that:


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|-- | ----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|1. | I have reviewed this amendment no. 1 to the
    annual report on Form 20-F (the Report) of
    Royal Dutch Petroleum Company (N.V. Koninklijke Nederlandsche
    Petroleum Maatschappij);                                                                                                                                 
|  
|2. | Based on my knowledge, this amendment does not
    contain any untrue statement of a material fact or omit to state
    a material fact necessary to make the statements made, in light
    of the circumstances under which such statements were made, not
    misleading with respect to the period covered by the Report;
|  
|3. | The companys other certifying officer and I
    are responsible for establishing and maintaining disclosure
    controls and procedures (as defined in Exchange Act
    Rules 13a-15(e) and 15d-15(e)) for the company and have:                                                                                           



| |     |                                                                                                                                                                                                                                                                                                                                                                                                                          
| | --- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | Designed such disclosure controls and procedures,
    or caused such disclosure controls and procedures to be designed
    under our supervision, to ensure that material information
    relating to the company, including its consolidated
    subsidiaries, is made known to us by others within those
    entities, particularly during the period in which this amendment
    and the Report is being prepared; and
|
| | (b) | Evaluated the effectiveness of the companys
    disclosure controls and procedures;                                                                                                                                                                                                                                                                                                                                     
|
| | (c) | [Intentionally omitted]                                                                                                                                                                                                                                                                                                                                                                                                  



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|-- | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
|4. | The companys other certifying officer and I
    have disclosed, based on our most recent evaluation of internal
    control over financial reporting, to the companys auditors
    and the audit committee of the companys board of directors
    (or persons performing the equivalent functions):



| |     |                                                                                                                                                                                                                                                                                       
| | --- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
| | (a) | All significant deficiencies and material
    weaknesses in the design or operation of internal control over
    financial reporting which are reasonably likely to adversely
    affect the companys ability to record, process, summarize
    and report financial information; and
|
| | (b) | Any fraud, whether or not material, that involves
    management or other employees who have a significant role in the
    companys internal control over financial reporting.                                                                                                       

/s/ Jeroen van der Veer

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Jeroen van der Veer

President and Managing Director


July 1, 2004



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