Laura Sadler is known to viewers as nurse Sandy Harper

Mal Young, BBC controller of drama series, said: "Laura's condition remains critical and unchanged from yesterday. Medical staff are doing all they can."

Actor George Calil, who plays her on-screen boyfriend in the BBC One drama, is understood to have been released on police bail after being arrested in connection with the incident.

A Scotland Yard spokesman confirmed that a 30-year-old man had been arrested, adding he would return in mid-July "pending further inquiries".

Ms Sadler, 22, was found at the foot of a house in Holland Park, west London, at 0630 BST on Sunday.

The house is in west London's Holland Park

She is thought to have suffered serious head injuries and was taken to Charing Cross Hospital in nearby Hammersmith, where she remains in a critical condition in the intensive care unit.

Ms Sadler, who plays Sandy Harper in the series, fell about 40ft (12m) from a rear second floor balcony into a basement stairwell.

Ms Sadler's agent also requested that the family are given space and privacy at this "difficult time".

Mr Young added: "The family are grateful for everyone's good wishes and support."

Co-star's shock

Holby City, a spin-off from the hospital drama Casualty, is watched by millions of people every week.

Ms Sadler first appeared on television in the children's series Grange Hill.

She has also appeared in a television version of Jane Eyre and Inspector Morse, Intimate Relations, the Ruth Rendell Mysteries and Belfry Witches.

Her Holby City co-star Art Malik spoke of his shock at the news during a GMTV interview to promote his debut on the programme on Tuesday.

Malik said: "I'm sure myself and every member of the cast and crew is praying for her, and my thoughts go out to her and her family."

He added: "My first line in my first episode was 'Morning Sandy. She was the first person I worked with."