The company said Mongeau, who had successful surgery that month to remove a rare type of soft-tissue tumor, was doing well and was now in the last stages of his radiation treatment.

The country's No. 1 railroad operator had said Mongeau required about three months of treatment and recovery, but would remain engaged in the business.

Chief Financial Officer Luc Jobin has been filling in for Mongeau.

(Reporting by Shubhankar Chakravorty and Sneha Banerjee in Bengaluru; Editing by Ted Kerr)