A taxi passenger has told of her shock as she watched a Melbourne taxi driver play games on his mobile phone while driving.

Lauren Ridgway tweeted the picture of the Silvertop cabbie when she spotted him allegedly playing games at the wheel while weaving through heavy traffic yesterday.

Ms Ridgway, who was returning to work after a business meeting in South Melbourne, claims the cabbie was using his iPhone for at least 15 minutes as the pair made their way along Toorak Road.

She claims the cab driver was so preoccupied with the 'Tetras-style' game he even failed to stop at a set of traffic lights.

"He was moving and had his phone down low and was just playing games," she said.

"This went on for around 10-15 minutes.

"It's certainly the first time I have seen anybody playing games while driving.

"It was a Tetras-style game...he was obviously trying to get a high score."

Ms Ridgway did not confront the driver directly about the dangerous activity.

She said she was more concerned with getting photographic evidence.

"I'm not really a confrontational person by nature. I didn't know how he would react if I did say something," she said.

Lauren Ridgway shocked after catching Melbourne taxi driver playing on phone while driving. Photo: 7News

She says she is outraged her safety was compromised.

"It was going through my mind that this guy is a professional driver, it's his job to make sure his passengers get safely from A to B. I certainly didn't think he was taking my safety seriously at the time."

The driver could soon have more playtime on his hands with the Victorian Taxi Directorate investigating the case.

The regulatory body says the driver could face disciplinary action, and possibly the sack.

"Taxi drivers should be taking our safety more seriously," Ms Ridgway added. "Playing a game is unfathomable. These people should really be setting an example of good driving. It's an accident waiting to happen."

Using a mobile phone while driving has been illegal in Victoria for the past 14 years.