London, Aug 4 : Dungeon dad Josef Fritzl’s son Felix, 6, is making miraculous progress after his horrific ordeal in the cellar, and can even ride a bike and swim.

According to reports, Felix rides his bicycle in the grounds of the Austrian hospital where he was taken along with his mother and other five siblings after being rescued by the police on April 26.

Now, the doctors have taught him various skills while he gradually re-adjusts to life after the dark years he was forced to spend in the cellar.

“They have been amazed at how Felix is adapting. He is really cheerful and fascinated by everything,” News of the World quoted an hospital insider as saying.

The source has revealed that the boy loves using the inflatable pool in the garden of the clinic flat, and knows how to use a mobile phone.

Felix has even made pals with other child patients, and loves playing Monopoly and Cluedo, according to the source.

This week marks 100 days since he was released from the cellar of Josef''s house in Amstetten, along with mum Elisabeth, 42, and siblings Stefan, 18, and Kerstin 20.

Felix’s recovery is all the more remarkable because doctors initially feared that he would struggle to walk properly and lead a normal life.

He is one of seven kids fathered by Josef during Elisabeth''s 24-year cellar sex slave ordeal. (ANI)