The Nasdaq-listed firm is selling additional bonds on top of the $200m raised from the sale in June of preferred ship mortgage notes.
Proceeds from the add-on will be used for general corporate purposes, Ultrapetrol said in a stock exchange announcement.
Credit ratings agency Moodys said the top up woulld not affect the rating on the company's stock.
Ultrapetrol owns river barges and operates in the offshore sector through Brazil-focused subsidiary, UP Offshore.
The
