Update - 11.34am: The National Lottery is defending an increase in the cost of its Lotto Plus games.
The price will go up by €1 from September 1 and will affect 90% of players who have been found to opt-in on the secondary draws.
A spokesperson for the company, Miriam Donohoe, said comments that it is the second increase are misleading.
Ms Donohoe said: "This is, in fact, the first rise in Lotto Plus 1 in 16 years, since 2002.
"This change does not apply to the main Lotto draw, it's wrong as such to suggest this is the second Lotto price rise since transition."
The cost of playing Lotto Plus is set to rise.
The price of a normal two-line ticket with Lotto Plus will go up by €1, with the prize fund set to increase from €500,000 to €1m.
It is the second rise in price since the National Lottery was bought by Canadian operator, Premier Lotteries Ireland, three years ago.
The increase will come into effect from Saturday, September 1.
A National Lottery spokesperson said: “There is no change in the price of a panel for the main Lotto Draw. We advised players through the press on August 4th of restrictions on advanced Lotto play due to exciting new enhancements to our Lotto Plus games.
"As well as extra prizes, the changes will include the top prize in Lotto Plus 1 doubling from €500,000 to €1,000,000. To support these enhancements there will be an increase in the price of a Lotto Plus line from 50 cent to €1, the first increase in 16 years.
"Almost 30 cent in every Euro spent on National Lottery games, including Lotto games, goes back to Good Causes all over Ireland in the areas of sport, youth, health, community, arts, heritage and the Irish language. Last year around €226 million was raised, amounting to almost €620,000 a day.
"We are always conscious of the need to offer fresh and exciting games to our players. The planned enhancements are based on player feedback and intended to improve the attractiveness of the game and maximise returns to good causes.”