For the next 40 years, the management of South Australia's lottery and Keno services will be managed by Tatts Group after the gaming giant shelled out $427 million to acquire its licence from the SA state government.

The deal "is also the highest valuation ever achieved for a lotteries transaction in Australia," noting that the amount that Tatts paid was higher than the sub $400 million that the government pegged as reserve price for the licence, said South Australian Jack Snelling in a statement.

"It significantly exceeds retention value and is substantially above our reserve price," he said.

The exclusive management agreement, where Tatts will be allowed to use the government-owned SA Lotteries' brands and products for 40 years, takes effect on Dec 10.

But those opposed to the licence sale believed the amount could have gone higher had those in authority had the proper perspective of fiscal management.

"The $427 million is equal to less than half of this year's budget operating deficit," Iain Evans, treasury spokesman, was quoted by The Australian.

Robert Brokenshire, Family First MP Robert Brokenshire, meanwhile said the proposal should have been first entered into an election, before any eventual awarding.

"Family First believes the state government had no mandate to make this sale and should have taken it to the people at the next election," he said in The Australian.

Mr Snelling defended that the SA government, under the deal's terms, still stands to receive $60 million in gambling taxes annually from the sale of lottery products.

"We are $20 million a year worse off but $427 million will be paid up front, which more than compensates for the $20 million loss but importantly it also protects the $60 million in gambling tax revenue we receive every year, which was at risk."

"South Australians will continue to be able to play the lottery games they enjoy, the government will continue to receive gambling tax distributions and there are now significant funds that the government can invest in things such as roads, hospitals, schools and infrastructure," Mr Snelling said.

Apart from SA, Tatts operates lotteries in Victoria, New South Wales, the Northern Territory, Queensland, Tasmania and the Australian Capital Territory.