People will not be allowed to supply other people's kids with booze in a private home without consent.

The measure is one of several that the Government has signalled ahead of an announcement later today of the detail of all the changes it has adopted after a Law Commission report released in April made 153 recommendations on reducing the harm caused by alcohol, including tax increases and a wide-reaching tightening of rules around the sale of alcohol.

The Government has ruled out pricing changes but has confirmed some measures.

Prime Minister John Key told Breakfast on TVNZ that the current lack of restrictions on who could supply young people with alcohol would change. At the moment the purchasing age for alcohol is 18 but that does not restrict other people supplying it in family homes. Under the change, permission for those under 18 to drink alcohol in a private home will have to be sought from their parents or guardians.

"I can tell you as a parent of teenaged children there is enormous pressure to supply alcohol, not just to them but to others," he said.

Mr Key said the Government had adopted or addressed 126 of the Law Commission recommendations; "so we are taking it seriously".

Measures include:

* a vote on a split drinking age - 18-year-olds can go to bars but the limit will be 20 for off-licences. The issue will be dealt with as a conscience vote, not a party one. Mr Key will vote for the split proposal;

* National opening and closing hours will be set. For an off-licence it will be 7am until 11pm. For bars it will be 8am to 4am;

* Local areas will be able to decide how many liquor outlets they have. They will also have a greater say on density, locality, hours of trade.

"What we have attempted to do is tackle the harm," Mr Key said.

"We think the harm is very young people 13-14-15-year-olds drinking; those legally able to purchase 18-24 and then some others. What we are doing is giving more powers, and this will be an important change, to parents and to individuals and to communities."

Supermarkets would continue to be able to sell alcohol but would be affected by licensing provisions, he said. The Government was also seeking more research before making a decision about whether to lower the alcohol limit for motorists, but has said it would be zero for people aged under 20.

The Government's plans have already been criticised as being "weak".

Labour MP Lianne Dalziel said it appeared the Government was tinkering rather than making substantial changes.

She said issues with cheap alcohol from supermarkets, an oversupply of outlets and other issues needed to be tackled and putting off lowering the drink drive limit was "ridiculous".

Sue Bagshaw, who works in youth health, said young people were targeted in changes when adults needed to start setting better examples.

She said alcohol needed to be less available and advertised and more expensive backed up by more treatment centres.

Alcohol Action spokesman Professor Doug Sellman, who is a National Addiction Centre director, said New Zealand was facing an alcohol crisis and from what he understood of the response it was like "treating cancer with a couple of aspirin".

"We expect widespread disappointment and anger when the public sees how little is really being proposed," he said.