Victoria makes it harder to win Oz Lotto

Three supplementary numbers will be drawn instead of two, resulting in 10 numbers drawn from 47.

The changes take effect on May 11 and decrease the odds of winning first division from one in 45.3 million to one in 62.8 million, the Victorian government gazette says. 

The move will affect Oz Lotto entrants in all states and territories since the Victorian-licensed game is played nationally every Tuesday. 

The Lott spokesman Matt Hart said the changes were made in response to feedback from lottery players.

"Players told us they wanted Oz Lotto to offer the potential for more winners and bigger prizes, and that's exactly what we've given them," he said.

"Oz Lotto has a history of delivering big multi-million-dollar jackpots every Tuesday, and these enhancements will allow us to continue to provide value to players."

Under further changes, he said Oz Lotto's base jackpot will increase from $2 million to $3 million and punters will be offered extra prizes, increasing the chances of winning other divisions from one in 55 to one in 51.

Opposition gambling spokeswoman Steph Ryan accused the government of making a cash grab, since the changes would lead to more tax revenue for Victoria.

"By adding extra numbers to the lottery, the government is ensuring that it's harder to win, which means it's going to jackpot more and bigger jackpots lead to bigger ticket sales," she told reporters on Thursday.

"This is just another desperate grab for cash from the Andrews government to try and plug its failure to manage its own budget.

"It's hard to imagine a more stingy move than making Oz Lotto so much harder to win."

Alliance for Gambling Reform chief advocate Tim Costello said the government was pursuing tax revenue over gambling harm reduction.

"There is absolutely nothing in this decision that reflects any approach to gambling harm reduction. It is simply driven by the Victorian government's desire to increase gambling tax revenue," he said.

Sport and Events Minister Martin Pakula dismissed concerns the game would be harder to win, saying the differences were "pretty academic".

Premier Daniel Andrews deferred to the state's Gaming Minister Melissa Horne and questioned the accuracy of opposition and advocate claims.

AAP has contacted Ms Horne for a response.