Ladbrokes has recorded a 32% year-on-year decrease in group operating profit for the first six months of 2015, from ¬£56.8m to ¬£38.9m.
The UK operator‚Äôs H1 pre-tax profit also dropped compared to the same period in 2014, from ¬£44m to ¬£24.7m.
The figures are 'headline' numbers which do not include high rollers or exceptional items.
The operator experienced net revenue growth of 1%, with UK retail also increasing 1% to ¬£410.5m and digital rising 7% to ¬£112.2m.
Sportsbook net revenue fell sharply over the same period, decreasing 26.3% from ¬£46.8m to ¬£34.5m.
Strong growth was recorded in the net revenue of Ladbrokes Australia, which grew from ¬£13.6m to ¬£25.4m year-on-year, an increase of 87%.
Ladbrokes chief executive Jim Mullen said: ‚ÄúOur first half results reflect the challenge facing Ladbrokes.
‚ÄúWhile we have some encouraging customer trends, we need to reset the business and invest.
‚ÄúThe results clearly show why we need to change and why we need to do so quickly.‚ÄĚ
However, the CEO noted: ‚ÄúThere are signs in H1 that the customer is there to be convinced by the Ladbrokes offer ‚Äď good gaming performance, strong mobile sportsbook KPIs and growth in Australia.
‚ÄúWe have a solid base to build on.‚ÄĚ
Ladbrokes agreed the terms of a merger with fellow operator Gala Coral last month, in a move that will lead to the creation of Ladbrokes Coral plc.
Mullen said: ‚ÄúThe proposed merger with the Coral Group represents an exciting opportunity for the business but, with completion some way away, the focus for me and my team must be on the here and now of delivering our organic plan, building a better Ladbrokes and driving performance towards our 2017 targets.‚ÄĚ