Wed Nov 7, 1:25 AM ET

NEW YORK (Reuters) - Whole Foods Market Inc amended its code of business conduct last week to restrict online activities by top officials, according to the company's Web site.

The updated code bans senior Whole Foods executives and directors from posting messages about the company, its competitors or vendors on Internet forums that it doesn't sponsor.

In July, Chief Executive John Mackey apologized to shareholders for posting messages on a Yahoo Inc chat forum under an alias for years. The postings talked up Whole Foods while criticizing rival Wild Oats Markets Inc, which it later bought.

Last month the company affirmed its support for Mackey after completing an internal investigation into his online postings.