Prince William has urged dads to be more open about their feelings and to discuss mental health with their children.

His message coincided with Father’s Day and he said that he wants his own children to be able to talk to him if they have problems, because he knows mental health is just as important as physical wellbeing.

The 33-year-old, who is father to George, aged two, and Charlotte, one, warned that unresolved mental health problems could “alter the course of a child’s life forever”, leading to issues such as addiction and even suicide.

In an article for the charity Heads Together, of which the Duke and Duchess of Cambridge, along with Prince Harry, are patrons, William said: “Today I celebrate my third Father’s Day as a father. For me it is a day not just to celebrate how fortunate I am for my young family, but to reflect on just how much I’ve learned about fatherhood and the issues facing fathers in all walks of life.

“In particular, it is a time to reflect on my responsibility to look after not just the physical health of my two children, but to treat their mental needs as just as important a priority.

“While the circumstances of any one situation are unique, it is clear that many families could have been helped if they had found it easier to talk openly about mental health challenges in the home.

“It is often said that fathers can often find it hard to talk about their own feelings so there’s no wonder they struggle to speak to their son or daughter about the topic.

“But we don’t really have a choice. I really believe that a child’s mental health is just as important as his or her physical health.

“A fifth of children will have a mental health issue by their 11th birthday. And left unresolved, those mental health issues can alter the course of a child’s life forever.

“So on this Father’s Day, I encourage all fathers to take a moment to ask their children how they are doing. Take the opportunity to discuss how you are coping with life and fatherhood with your wife, partner or with your friends.

“And know that if your son or daughter ever needs help, they need their father’s guidance and support just as much as they need their mother’s.”