July 20 (Reuters) - Canadian National Railway Co on Tuesday reported a 12.1% rise in quarterly revenue, as the country's biggest railroad operator shipped more petroleum, chemicals and intermodal freight.

Total revenue rose to C$3.598 billion ($2.84 billion) in the three months ended June 30 from C$3.21 billion a year earlier, when the pandemic hit freight volume.

Canadian National has agreed to a $33.6 billion deal to buy smaller U.S. railroad Kansas City Southern, and the planned merger is being scrutinized by regulatory authorities. ($1 = 1.2674 Canadian dollars) (Reporting by Abhijith Ganapavaram in Bengaluru; Editing by Devika Syamnath)