TTC union boss Bob Kinnear has warned transit workers that a "ridiculous" crackdown on cellphone use could see them fired for using their phones while on break.

Kinnear sent a message to union members on Sunday saying the TTC is being overzealous in its policing of phone use since three operators were caught using phones while driving in January. He says the union has been seen about 20 cases of operators being fired for using phones in circumstances where public safety was not affected.

"Last Thursday, a female bus operator was assaulted by a passenger," states the message sent to all members of Amalgamated Transit Union Local 113. "As the assailant was leaving the bus, which was not moving at the time, she took out her cellphone to take a picture of him. She then reported the assault to management and showed them the picture. She was fired on the spot."

Kinnear said the union was able to get the worker's job reinstated, while TTC management says she was merely suspended, not fired.

A transit commission spokesperson could not confirm the extent of discipline against other employees since the January incidents. Brad Ross denied there was a cellphone crackdown afoot, but said the agency is considering a policy to force drivers to keep their phones in bags instead of on their person.

Kinnear's statement said the union will continue to defend employees' rights to use their cellphones while on break and not behind the wheel of a vehicle, and in situations where passenger or driver safety is at risk.

Kinnear believes Mayor Rob Ford has ordered TTC management to enforce the crackdown. He claims the mayor wants to provoke a reaction from the union that will justify his push to declare the TTC an essential service, making strikes illegal.

Several calls to Ford's office on Monday were not returned. But in a Monday interview with a Toronto newspaper, his staff denied claims he was behind such a crackdown.

"Chief General Manager Gary Webster is enthusiastically going along with this in order to make himself look tougher on the union so that he can keep his quarter million dollar a year job," Kinnear's statement reads, promising more information in the coming days. "In the meantime, please continue to perform your work to the best of your ability, given the sorry state of our under-funded transit system."

The essential-service legislation, known as Bill 150, was introduced by Ontario's Liberal government at Ford's request and could be passed by March 24. Labour contracts for the TTC expire March 31, leaving a week-long period when the government can pass the law.