The endorsement from proxy advisory firm Glass Lewis is the second major endorsement for the diversified miner. Earlier this week, Institutional Shareholder Services (ISS) also advised its clients to back the company's nominees over a slate put forward by Armoyan, saying "the dissident has not made a compelling case for change to the board level at this stage.

Proxy advisory firms such as Glass Lewis and ISS advise major institutional investors ahead of shareholder votes. Their reports often influence votes for or against management in proxy battles.

"With unanimous support from the leading proxy advisors, momentum is clearly behind Sherritt's director nominees," Sherritt Chairman Harold Stephen said in a statement on Thursday.

(Reporting by Euan Rocha; Editing by Dan Grebler)