Tommy Lee and son Brandon Lee reignited their feud by slamming each other on social media on Father's Day (17Jun18).

The former Motley Crue rocker was hospitalised after the 22-year-old, his son with Baywatch star Pamela Anderson, knocked him unconscious when a heated argument turned physical at his home in March.

It seemed they had made amends when Brandon told TMZ he loved his dad shortly afterwards, and Tommy declined to co-operate with police on a battery investigation into the incident, so the case was closed.

However, their feud reignited on Sunday, when the rocker posted an old photo on Instagram of himself with his father and shared how being a dad to Brandon and his younger brother Dylan "ain't easy".

"Sometimes I feel like I failed as a father, because my kids don’t know the value of things," he wrote. "If they break something, they don’t care because they know they’ll just get a new one, if they hurt someone, they don’t care because so many people tell them it’s OK. I never wanted this for my kids."

Bringing in Pamela, he added, "I know I’m not fully to blame, because their mom has a lot to do with it, enabling bad behavior and buying them things when they weren’t good, but I guess I hoped at the end of the day they would end up kind.

"I love them dearly, don’t get me wrong, but man, sometimes it’s really tough to watch your kids grow up without those morals. Nothing can really prepare you for fatherhood .... I love my boys but they can be a*sholes too...and that’s the truth (Cue Honest Guy music)."

Brandon took a screengrab of Tommy's caption and blasted him for painting the family "in a negative light" again, and reminded him of what happened last time he spoke badly about his family.

"Remember what happened last time you said this s**t? night night," he wrote, before claiming Tommy never showed up to birthday or baseball games. "Who the f**k are you? Just move on dude... WE ALL HAVE. or I’ll put you right back to f**king sleep."

He followed it up by sharing a video of Tommy passed out on the floor in a T-shirt and underpants, seemingly from the incident in March.

"Look a little sleepy there Tommy," he wrote in the caption.