A Tauranga bus driver is questioning teenagers' accessibility to alcohol after noticing an alarming trend of underage drinking onboard Bay Hopper buses.

The Bay Hopper driver, who will not be named, contacted SunLive with concerns after an incident on Saturday that involved a dozen boys and girls under 16-years-old drinking on the bus.

The group boarded the bus in downtown Tauranga City heading and got off at Merivale Community Centre.

During the bus ride, the group were seen drinking ready-to-mix drinks, particularly 250ml Cody's Bourbon and Cola that range from five to eight per cent in alcohol.

'When they got off, their seats had the empty Cody's bourbon cola cans,” says the driver.

'I saw them drinking in my mirror while I was driving; I know they are all under 16. That's not the first time; you get kids coming along all the time with RTD's.”

The driver, who has worked on Bay Hopper buses for five years, believes this a worrying trend. He says it spikes during school holiday periods and he is becoming increasingly concerned about the ability of teens to access alcohol.

'How do they get it in the first place at that age, that's the concerning thing? Particularly when they aren't event 16, they are still kids.

'I was just distraught that there were so many of them in one hit; and all getting off at the same place. Nine times out of ten they don't have it in their hands when they get on the bus.”

Tauranga Safe City coordinator Mike Mills suggest underage teens are having adults 'primed” to supply alcohol or are approaching adults as they enter the stores.

'I haven't had that behaviour reported to me but it's a traditional way if you like that young people get alcohol is they will sit outside a store and see an likely person and say ‘could you get us a six pack or something',” says Mike.

'So my message really is to not target the off-licence per say, but it is again a message back to people purchasing for young people that they are breaking the law.”

Mike says RTD's remain a worrying concern for the industry and alcohol officials with a harsher stance needed on preventing such mixes getting into the hands of young people who are unable to handle substances.

'They are small cans so they are easily hidden. The RTD's have always been a worry because their target market is young people and it's easily hidden in a carry bag and that's well evidenced.”

A Go Bus day supervisor, who would be named as John, says there have never been any reports of underage teens drinking on any of the company's services.

When questioned what the company's stance is regarding alcohol on buses, the supervisor says there is no such protocol because this has never been a problem.

'Well there is no drinking on public services. They would probably be put off the bus all depending on the situation concerned and the emergency services called,” he says.

'It's never happened so we haven't come across that problem. We have had no reports whatsoever.”