The head of BlackBerry Messenger has become the latest in a string of top executives to depart the struggling smartphone maker.

However, the brief email announcement issued by the Waterloo, Ont.,-based concern shed little light on the departure of BBM head Andrew Bocking.

"I can confirm that Andrew Bocking, EVP, BBM has made the decision to leave BlackBerry. We thank him for his years of leadership and contribution," company spokeswoman Rebecca Freiburger said.

Freiburger said John Sims, president, Global Enterprise Solutions, who has extensive experience in mobile messaging, would add the BBM team to his organization.

BlackBerry head John Chen has made wholesale changes in the company's executive offices since taking over as chairman and CEO back in November.

In addition to the many long-time executives who have left, Chen has brought in a number many new faces, including many people he has worked with in the past.

BBM, which is currently free to users and does not carry advertisements, is a service that Chen has indicated he wants to monetize. However, he has not said how the company plans to do this.