BOSTON -- A new rule banning MBTA operators from carrying cell phones has been expanded to include employees on commuter rail trains, commuter boats and private cars and buses contracted by the T, officials announced Sunday.

The cell phone ban, which already prohibits bus, trolley and subway operators from carrying electronic devices, will now be adopted by MBTA service contractors, including the Mass Bay Commuter Rail and several private companies that provide transportation through the RIDE para-transit service. The ban will also affect the commuter boat service and two companies contracted to provide ferry transportation.

Under the stricter policy, which went into affect May 18, employees who carry or use an electronic device on the job will be suspended with a recommendation for dismissal.

"Public safety and customer service must continue to be our number one priority and I'm thankful the MBTA's contractors are joining us in implementing a zero tolerance policy for cell phone use," said Transportation Secretary James A. Aloisi Jr.

The new round of cell phone regulations follows a crash between two Green line trains last month that injured 50 people. The driver of one of the trains told police that he was texting his girlfriend moments before the crash.

A previous policy at the MBTA banned operators from using electronic devices on the job, but disciplinary action was limited to a three-day suspension after one offense, followed by a 10-day suspension after two, and dismissal for the third offense.