The Scottish Government has reintroduced its plan for minimum alcohol pricing.

The SNP administration had been blocked by opposition parties when it tried to set a floor price per unit last year but now has a majority in the Scottish Parliament.

Health Secretary Nicola Sturgeon said: "Scotland's unhealthy relationship with alcohol is one of the most pressing public health challenges facing us as a nation and we need to take action to tackle it.

"Here we have a second opportunity to add the missing piece in the legislative jigsaw: introducing minimum pricing. I urge my parliamentary colleagues to take it."

Last year the price was expected to be 45p per unit but no official limit has yet been set.

The policy was widely supported by police and health professionals but opposed by some trade bodies and opposition parties. The Liberal Democrat group has changed its position and is likely to support the Government.

Ms Sturgeon continued: "We should not lose sight of what has been achieved during the last four years. We have had a wide-ranging debate on alcohol pricing and there is now widespread recognition across the country of the need to tackle pricing.

"We have introduced a ban on quantity discounts and promotions in off-sales have been restricted, but already we have seen that without minimum pricing these attempts to take action on Scotland's alcohol problem are being undermined.

"By setting a minimum price for a unit of alcohol, we can raise the price of the cheap supermarket white ciders, lager and value spirits sought out by problem drinkers.

"I hope that this time around MSPs will do the right thing and back this policy that has the support of doctors, nurses, the police and growing numbers of the general population.

"I will not shirk from leading the way in addressing this challenge. It is time for Scotland to win its battle with the booze."

Based on a 45p limit, the minimum price for a standard 700ml bottle of spirits at 37.5% ABV would be £11.82.

A 500ml can of super-strength 9% beer would be £2.03, while a bottle of 12.5% wine would cost a minimum £4.22. A two-litre bottle of 6% cider would cost £5.40.

To calculate the total, a formula was used to multiply the suggested minimum price by the strength of alcohol and the volume of alcohol in litres.

The Government argues that alcohol-related problems cost Scotland £3.56bn each year, equal to £900 for every adult.

The University of Sheffield, which conducted research on the original proposal, is having a fresh look at health data from 2010.

Minimum pricing was rejected in a 76-49 vote at Holyrood in November last year when MSPs were debating the wider Alcohol (Scotland) Bill.

However, MSPs approved a ban on discount deals, such as two-for-one bottles of wine, and restricted "irresponsible" drinks promotions and advertising around premises.

The Bill established a requirement for age verification and paved the way for a new tax on licence holders, called a social responsibility levy. The tax aims to ensure retailers and licensed premises, such as nightclubs, contribute to the wider cost of their activities to the community.

The SNP pledged to push ahead with the alcohol price plan in its election manifesto. The party was elected with an unprecedented majority in May this year.

Dr Brian Keighley, chairman of the British Medical Association in Scotland, said: "It is simply wrong that alcohol is sold at prices cheaper than fizzy drinks.

"If our politicians are serious about helping to change our Scots culture of heavy drinking, then they must support the Government's minimum pricing Bill. Without addressing price, many of the policies we've introduced already will be rendered less effective.

"There is an urgent need to legislate. For too long supermarkets have been piling it high, selling it cheap when it comes to alcohol."

But Jeremy Beadles, chief executive of the Wine and Spirits Trade Association, said: "As millions of families face the toughest economic conditions for a generation the Scottish Government is determined to press ahead with legislation that will punish the vast majority of responsible consumers with higher prices.

"Yet there is no evidence minimum pricing will address the problem of alcohol misuse and the most recent Government figures show alcohol consumption per capita fell in Scotland last year.

"The Scottish Parliament should insist on its right to review the policy and its impact on cross-border shopping, internet sales of alcohol and any evidence of illegal trade of alcohol in Scotland."