COLLINGWOOD'S Harry O'Brien admitted to battling personal 'demons' as he returned to training on Tuesday morning. 

He spoke of "a long and very complicated history of sexual abuse", suicide, depression and of having seen a murder but being too afraid to go to police because of fear for his own life. 

O'Brien's stunning revelations came in a door-stop interview when he returned to the club after personal leave. 

The Magpies defender spent several days in Port Douglas after a bust-up with coach Nathan Buckley during a team meeting. 

O'Brien said he was struggling to deal with the issues he was confronting under the glare of public scrutiny. 

"I'm going through issues that I sort of put in the past for a long time, including a long and very complicated history of sexual abuse. 

"Suicide, depression, seeing someone get murdered knowing who'd murdered that person and not being able to say anything because that person would probably murder you." 

O'Brien has previously spoken publicly about witnessing a murder on Christmas Day, 2011, while on holiday in his birthplace Brazil. 

"[I'm] going through quite a tough time at the moment. I just ask you guys for your sensitivities to that," he said. 

"When the time comes right I will open up about these issues. 

"This is my personal experience and I have to do this in the public eye and it is really tough, so if you guys can give me a bit of space because I am going through some real stuff here." 

Collingwood president Eddie McGuire said on Triple M radio he had been aware of O'Brien's issues, but did not know he would reveal his condition publicly.

"This is all about trying to do the right thing, to get him back.

"We have got the best doctors, the best psychiatrists, the best psychologists all working on the case.

"We love the guy, so just give him some space."

 Harry O'Brien with his teammates at Collingwood training on Tuesday. Picture: AFL Media

O'Brien praised the club before heading into the Magpies football department. 

"Whatever you guys have been reporting, that is secondary, this is my real stuff," he said. 

"The club has been fantastic in supporting and protecting me and they have tried to do that. I ask you guys to cooperate because I am going through some real stuff here." 

O'Brien, 26, became the centre of a media frenzy when he took his break from the club after his argument with Buckley. 

He was also suffering an ankle injury. 

Harry O'Brien and Luke Ball go through their paces at training. Picture: AFL Media

Buckley refused to comment publicly on what was discussed, but met with O'Brien on Monday, when it was agreed that the premiership player and All Australian would return to training on Tuesday. 

O'Brien has been a strong advocate on a range of social issues, and had a run-in with McGuire over his now-infamous King Kong radio gaffe.

He led the team out on to the track on Tuesday morning and appeared to train without being hampered by his ankle. 

People seeking help or information about depression can contact Lifeline, 131 114, www.lifeline.org.au or Beyondblue, 1300 224 636, www.beyondblue.org.a