Daniel Radcliffe has revealed he sent a letter to the actor playing Harry Potter in the forthcoming TV adaptation.

The actor said Dominic McLaughlin, who is taking over the role for HBO's reboot, then sent him "a very sweet note back".

Radcliffe, who played the famous schoolboy wizard in the decade-long noughties film franchise, told Good Morning America he wrote directly to McLaughlin after the child star was cast in the lead role.

His predecessor - who was also 11 years old when he began work on the first Harry Potter movie - wished the youngster and his co-stars all the best for the production, saying: "I just want to hug them."

McLaughlin will star opposite Arabella Stanton as Hermione Granger and Alastair Stout as Ron Weasley.

Radcliffe said: "I don't want to be a spectre in the life of these children, but I just wanted to write to him to say, 'I hope you have the best time, and an even better time than I did - I had a great time, but I hope you have an even better time'."

"And I do, I just see these pictures of him and the other kids, and I just want to hug them."

He added, "They just seem so young. I just look at them and say, 'Oh it's crazy, I was doing that at that age.' But it's also incredibly sweet, and I hope they're having a great time."

An open casting call for the roles was announced last year, and more than 30,000 children auditioned.

The chosen ones - McLaughlin, Stanton and Stout - are all relative newcomers.

McLaughlin previously appeared in Grow, a Sky comedy with Nick Frost and Golda Rosheuvel, while Stanton starred as Matilda in the musical of the same name in the West End. Stout had no prior acting credits.

The young cast of the new series also includes Lox Pratt as Draco Malfoy, Alessia Leoni as Parvati Patil and Leo Earley as Seamus Finnigan, as well as Rory Wilmot who will play Neville Longbottom and Amos Kitson portraying Dudley Dursley.

They will be joined by adult stars including John Lithgow as Albus Dumbledore, Janet McTeer as Minerva McGonagall, Paapa Essiedu as Severus Snape, and Nick Frost as Rubeus Hagrid.

Filming is under way for series one of the new show, which is set to launch in 2027.

But the entire production is expected to take 10 years to complete in total, as the plan is to film a series to cover each of JK Rowling's seven books, which the films were originally based on.

With that in mind, Warner Bros Studios in Leavesden near Watford, where it is being made, was this summer granted permission to build a temporary school for the child actors to study in for real, when they're not at Hogwarts.