NHK said Friday that effective the same day it is prohibiting, in principle, stock trades by reporters and other employees who have access to its news information management system.

The ban was introduced following the revelation earlier this year that two reporters and one director made share transactions using information obtained from the system. All three were fired in March.

Around 5,700 employees who have access to the news information system at NHK and its affiliates will be required to pledge in writing that they will not trade in stocks, and those who fail to do so will not be given access to the system, NHK said.

NHK employees who do not have access to the system are banned from engaging in short-term stock trading.