The Government's liquor law bill passed its first reading in Parliament today amid strident criticism from opposition MPs who said it would do little to curb binge drinking or reduce the harm alcohol caused.

The Alcohol Reform Bill will enact previously-announced proposals, a raft of law changes affecting the sale and supply of liquor.

It gives local authorities strong powers to decide their own licencing regimes, proposes splitting the purchase age to 18 for bars and 20 for supermarkets and liquor stores, puts restrictions on the supply of liquor to minors and extends the description of public places where drinking can be banned.

Justice Minister Simon Power said risky drinking was becoming increasingly normalised in New Zealand, especially among young people.

"The Government is not going to stand by and allow excessive and harmful alcohol consumption to become further ingrained into our culture," he said.

"Legislation alone won't change our excessive drinking culture.

"It can, however, help us develop a safe and responsible drinking culture, supported by robust public education and treatment interventions."

Labour's justice spokeswoman, Lianne Dalziel, said the Government had squandered a once-in-a-generation opportunity and had "gutted" the Law Commission's report which was the basis for the proposals.

"This bill doesn't even begin to meet the challenge posed by the evidence that the Law Commission presented to the Government," she said.

"The Government has ignored evidence that at least four other matters had to be addressed - lifting the price of the cheapest alcohol, the excessive commercialisation of alcohol, constraints on marketing New Zealand's number one recreational drug, and introduced stronger laws relating to alcohol and driving."

Ms Dalziel said the Government had seriously under-estimated the understanding the public had about the harm alcohol caused and had caved in to industry arguments.

"The Food and Grocery Council has had more influence that the Law Commission," she said.

Sue Kedgley, from the Greens, said the Government had blown an opportunity to tackle alcohol problems because it didn't have the courage to stand up to the liquor and supermarket industries.

"We live in an alcohol-saturated society, there are more than 14,500 outlets," she said.

"Harmful drinking is so widespread it is seen as normal...supermarkets are selling alcohol at below cost to get people in their doors."

Maori Party MP Hone Harawira said his MPs would support the bill but didn't believe it would make much difference.

"Very little change will come about because of this bill," he said.

"Governments continue to tinker with the law while Maori continue to die from the effects of alcohol."

The bill passed its first reading on a vote of 114-3. The only opposition to it came from three Act MPs, while the party's other two MPs supported it.

The bill has been sent to the justice select committee which will spend at least six months hearing public submissions on it.