Police and Hamilton's mayor are not impressed with the number of licensed premises selling liquor to under-age drinkers. Belinda Feek reports on a weekend crackdown.

A 14-year-old was found boozing in a Hamilton bar on Saturday night during a police operation in which a fifth of licensed premises visited sold alcohol to underage drinkers.

The discovery has shocked police and Mayor Julie Hardaker, who took to the streets with police, with Ms Hardaker slamming it as "unacceptable" and "disappointing".

More than 140 Waikato police took part in Friday and Saturday nights' Operation Unite, part of a national crackdown on alcohol and violence.

Waikato district police commander, Superintendent Win Van Der Velde, who was among officers involved, said of the more than 60 on and off-licence premises checked in the district, 13 sold liquor to an under-age volunteer used by police.

Meanwhile, the 14-year-old found drinking in a Hamilton bar, which police would not name, was taken home by police.

Mr Van Der Velde said it was not a good look for licensees caught out, especially as there had been plenty of warning prior to the weekend operation.

"This reflects a lack of responsibility on the part of licensed premises responsible for the safe sale of alcohol to the public."

Darrel Hadley, of Phoenix Group, whose stable of city bars includes Rodeo Rodeo and CBD, said the teen drinker was not caught at one of his bars but he was shocked someone so young slipped through security.

"I would like to think this is a shocking exception. Hamilton, from my perspective having worked in other cities, is right up there in terms of monitoring."

His staff had noticed an alarming increase in underage people borrowing the identification of their older siblings to get in. But pub staff should still be able to tell the difference, especially if confronted with a 14-year-old.

"You can borrow all the IDs in the world but you're still 14."

Mayor Hardaker, who joined police for the operation on Friday night, said bar owners all knew the rules and whoever served the 14-year-old should have known better.

"The rules around underage drinking are very clear."

Mr Van Der Velde and Mrs Hardaker would discuss the results of the sting later this week with those caught to be dealt with by the Liquor Licensing Authority.

More than 3700 drivers were stopped in the drink-driving crackdown, resulting in 55 positive tests while 14 others are awaiting blood test results. This made up almost a third of the national total of drink-drive busts during the weekend.

Mr Van Der Velde said too many intoxicated drivers were on Waikato roads.

That included two men who had been drinking who both claimed to be the driver of a car which crashed into another vehicle at the intersection of Bandon and Greenwood Sts at 7.30am yesterday.

The Times joined Waikato highway patrol Senior Sergeant Jeff Penno on Friday as his team carried out vehicle stops, booze checks and licensed premise checks in Matamata, Morrinsville and Hamilton.

After five hours in Matamata, police had busted five people.

Acting Sergeant Darin Frost was unimpressed given police were not hiding from residents. "We're doing unfortunately well," Mr Frost said from his post on Broadway.

Over in Morrinsville, Sergeant Vic Sneddon was relatively happy until his team busted their first drug-impaired driver in the town.

The number of young, drunk females getting into trouble due to alcohol was also a focus, with Mr Van Der Velde astonished at what little they were wearing. "Obviously parents have to take some responsibility but not when you see the amount of clothing they're wearing, and the amount of alcohol they've consumed."