Police now have wider powers to search people with metal detectors and ban them from Adelaide's west end entertainment strip, the South Australian Government has said.

The Government said the state's "first declared public precinct" covered a section of North Terrace, West Terrace, Currie Street and King William Street and includes popular Hindley Street.

The precinct will be in force from 6:00pm to 6:00am on Fridays and Saturdays starting this weekend as police try to curb antisocial behaviour.

"If you are out and about having dinner or a drink with friends and family you should not have to put up with any person or people who are highly intoxicated," Attorney-General John Rau said.

"It's quite simple, if you don't like the idea of being searched by police, or asked to move on, don't be a menace on the streets."

The Summary Offences (Declared Public Precincts) Amendment Bill was passed in October last year after a period of public consultation in March 2016.

Police will now have the powers to use metal detectors to search people, ban people in the area during specific times and remove children under the age of 18 if officers considered they were at risk.

"SAPOL welcomes this legislation as it allows police to effectively manage inappropriate behaviour in real time without the need to be unduly tied up with arrest documentation or administrative burdens," Deputy Police Commissioner Linda Williams said.

"We expect this to help police manage unruly and disorderly behaviour.

"The designated city west area will be a safe space for families and law-abiding members of the community, it will not be a welcoming space for drunken idiots and criminals."

Police will be able to search people for weapons and drugs in the precinct on Friday and Saturdays from 6:00pm to 6:00am. ( Supplied: South Australian Government )

New rules 'run the risk of backfiring'

The SA Council for Civil Liberties said it supported the bill but SA Greens MLC Mark Parnell called them an "overreach because they allowed police to target people who are doing nothing wrong, nothing illegal".

"The idea that you can be stopped and metal detected outside a high-end restaurant in Leigh Street or somewhere else in the West End without the police having to suspect you of having done something wrong or are about to do anything wrong, these laws have the potential to backfire," he said.

"They run the risk of backfiring because if young people feel that they're being harassed or hassled then it's likely to escalate tensions rather than what we really want, which is everyone out having a good time and keeping the level of anxiety as low as possible."

Mr Parnell said the laws were aimed mostly at young people, which led to the Youth Affairs Council, the Law Society of SA, and the Aboriginal Legal Rights Movement all coming out "strongly against these laws".

"We will need to have an audit and review the operation of these laws because there could be some terrible unintended consequences," he said.

"We'll have a look at the statistics. We'll find out how many people were moved on, how many people were issued barring orders and hopefully we can get some statistics on whether levels of conflict in this zone actually increased as a result of these police powers.

"But, the laws are coming in, we just now need to trust that the police will exercise them responsibly and sensibly."