The Batman v Superman: Dawn of Justice star, 44, has three young kids with estranged wife Jennifer Garner - Violet, 10, seven-year-old Seraphina and four-year-old Samuel.

And the actor's protective feelings towards his offspring mean he feels as vulnerable as a young child himself.

Ben tells America's People magazine, "When you have kids, what's that expression, 'Your heart is outside your body,' all of the sudden you feel so vulnerable and this fear of a child being vulnerable is very very powerful."

As well as his fears over his children's welfare, Ben frets about whether he is making the right choices in terms of bringing them up.

"I face dilemmas that we all do everyday about what's the right way to raise children, what's the right thing to teach them?" he explains. "Every moment there comes a crossroad."

Ben and Jennifer, 44, announced their decision to divorce in June last year (15). They have however remained on good terms and have spent time living together with their children.

The actor's new thriller The Accountant sees him play Christian Wolff, a mathematics genius whose emotionally stilted personality results in him having a difficult relationship with his son.

And the star says the film's complex take on parenting is in part what drew him to the role.

"Here's a guy out of love and compassion and fear for his son, actually ends up kind of brutalising him and abusing him and it's a really interesting look at what's the appropriate way to channel the intense emotions we have as parents, it's not easy," he explains.

The Accountant, which also stars Anna Kendrick and J.K. Simmons, opens in theatres on 14 October (16).