The six-year-old French boy who was seriously injured after being thrown from a viewing platform at London’s Tate Modern has started to speak again, his family have revealed.

In a post on a GoFundMe page that has raised more than £143,000 for the boy’s treatment, his relatives said he was also regaining sensation in his limbs.

A message passed on from the family said: “We have very good news to share with you. Our little knight begins to speak! He pronounces one syllable after another, not all of them, and most of the time we have to guess what he means, but it’s better and better. It’s wonderful progress!”

The message suggests the boy’s parents refer to him as a knight because of his “full armour of splints”, which are still in place nearly five months after the incident.

The family said the return of feeling in the boy’s limbs had been a very painful experience for him.

“He also begins to move his four limbs now. It is very difficult to see it concerning his left arm and hand, but it’s really slowly beginning to move,” the statement said.

“However, as he begins to move, sensations come back and he feels more pain, above all during the night, which is very exhausting for everybody, but he is very courageous and we stay strong for him.”

The boy, who cannot be named, was thrown off Tate Modern’s viewing platform on 4 August by Jonty Bravery, who was 17 at the time.

Bravery, who has autism, pleaded guilty to attempted murder at the Old Bailey this month and he will be sentenced in February. He has said that at the time of the offence he had wanted to highlight his frustration over the treatment of his mental health problems.

In their statement, the family thanked everyone who had contributed to the fund. “Your help makes it possible to offer our son the best rehabilitation, and for us to take care of our little boy every day, to stay with him as long as he needs with the best doctors and therapists. Thank you also to keep us strong with all your kind messages. You can’t imagine how much it is helpful.”