1. The reviewer informs the editor of the CoI not revealed by the order

2. Thank the reviewer and inform him that you plan to investigate
3. Contact the author(s) and express your concern

In the latter there are two alternatives:

A. The author(s) provide the relevant details, then:

• Thank the author but indicate that this is a serious omission
• Amend, if applicable, the conflict of interest declaration
• Proceed with review and publication
• Inform the reviewer of the result

B. The author(s) deny that there is CoI

• Clearly explain the journal policy and definition of COI, and obtain from each author a signed statement on all relevant COI

NOTE:

To avoid future problems:

Always obtain, from all authors, a signed COI statement before publication (or indication on a checklist or form that there are no conflicts)

Check that the journal's standards include a clear definition of CoI