DUBLIN (Reuters) - Flutter raised its full-year guidance after a much better than expected second quarter and said it has no plans "at this stage" to follow rival Draftkings ( DKNG ) in adding a surcharge to customer's winnings in high-tax U.S. states.

Flutter, the world's largest online betting company, expects to boost its previous forecast for a jump of around 30% in full-year core profit thanks to a 17% rise in second-quarter profit, bookmaker-friendly sports results and third-quarter momentum.

It expects core profit of $680 million to $800 million in its U.S. Fanduel brand versus the $635 million to $785 million seen in March and last year's $167 million, which was its first full year of profitability in the rapidly growing market.

Core profit of $1.69 billion to $1.85 billion is now seen its others markets, which include the Paddy Power and Betfair brands in Britain and Sportsbet in Australia. That compares to the $1.63 billion to $1.83 billion forecast previously.