The Challenge: Identify man in watermark on Mauritania's notes

Today’s challenge is to identify the following man whose face appears as the watermark on all of Mauritania’s notes since 1974.

If you can precisely identify the name of this man—or have a lead which you think might be useful—please post a comment, preferably including a URL which links to evidence supporting your identification.

This man’s face appears as the watermark on all of Mauritania’s notes since 1974, and is shown here from an unissued specimen design of 1981: