Anthony Siebold has stepped down as head coach of struggling NRL club Brisbane Broncos, effective immediately.

Embattled boss Siebold announced his departure on Wednesday, less than two seasons into a five-year deal, amid Brisbane's woes and intense speculation over his coaching future and personal life.

Siebold – who arrived from South Sydney Rabbitohs as the 2018 Dally M Coach of the Year – was also placed in isolation for 14 days after leaving the Broncos' coronavirus bubble to deal with a personal matter.

Peter Gentle will take charge for the remainder of the season, with the Broncos languishing 15th in the table after managing just three wins heading into round 16.

"From a professional viewpoint, this was the hardest decision I have ever made. Right now, I want to spend more time with my family. They have made enormous sacrifices for me in recent times," Seibold said. "I was honoured to be appointed Brisbane Broncos coach at the end of 2018. This was the club where I started my rugby league journey as a young man and it's a club that I have always admired.

"For many reasons, my time at the Broncos did not work out as we had all hoped. But that's sport. We love sport because it's full of uncertainty. And rugby league seems to throw up uncertainty better than any sport I know. People ask me if there are things I'd change about the last two seasons. None of that matters right now.

"I gave it my best at the Broncos and I am responsible for where we currently are. Head coaches know that there is no finger-pointing and no deflection of blame when a club struggles.

"These events haven't dampened my enthusiasm for coaching or wanting to help others achieve. In fact, they have made me more determined. Head coaching in the NRL isn't for the faint of heart. I know that. And I know that I'll be a better coach, a better leader and a better person for all that I have learnt over these last three seasons at South Sydney and Brisbane.

"I have very much appreciated the messages of support from many people over the last two weeks. I want to thank them, and I want to let them know that I’m doing ok.

"I have appreciated the opportunity to coach the Broncos. I thank Karl Morris and Paul White for their work and their advice throughout my time here. They run a very successful club and they should be proud of what the Broncos achieve in shaping so many lives for the better across Queensland. This club is more than what happens on the football field and I've been privileged to see that up close.

"I thank the Broncos fans. I've had plenty of well-wishers and I've had plenty who haven't been as impressed. Sport only succeeds because of the passion of the fans. Without them, we have nothing.

"Most of all, I'm appreciative of the opportunity to be a football coach, working with young men towards a common goal. I thank my players over these last two seasons for their effort, for their camaraderie and for their passion for playing football. Our game is a brutal game physically."

Broncos chief executive Paul White added: "As you are aware, Anthony spent the last two weeks in home isolation after having to step out of the Project Apollo bubble for a serious family matter. During that time, Anthony has reflected on his role at the Broncos and the impact it is having on his life away from rugby league.

"As a result, Anthony approached Chairman Karl Morris late last week to indicate he did not wish to continue as coach of the Brisbane Broncos. The Board understands Anthony's situation and has accepted his wishes to step down from the position.

"The role as coach of the Broncos is one of the most high-profile and high-pressure in Australian sport, and Anthony has performed admirably since starting in late 2018.

"But the levels of scrutiny – some of it bordering on hysterical, if not slanderous in recent times – have placed a heavy burden on Anthony and his family.

"As a club, we have endeavoured to support Anthony and his loved ones through all of this. But at the end of the day only Anthony can understand what it is like to walk in the shoes of a Broncos coach, and live with the highs and lows of the role.

"On a personal note, I would like to thank Anthony for the tremendous amount of effort and diligence he has poured into the job during his time at the Broncos.

"He can certainly coach, he will coach again, and he is also a very good man. He has always acted with the utmost professionalism and ushered in a new generation of stars who will become household names for our club in the future. As a club, we wish Anthony and his family all the best in the future."