A charity has called for improved security at Chase Farm Hospital after a patient escaped from its mental health unit.

Mental health charity SANE is concerned after Christopher Studders disappeared last week while walking in the hospital grounds.

The 40-year-old, who was detained under the Mental Health Act after pushing two women off a Tube platform, returned to the hospital the following day, but his disappearance raised serious security fears.

Marjorie Wallace, chief executive of SANE, said: "With confidence in care in the community at an all-time low, SANE believes it is essential that those in secure care are accompanied by escorts at all times when they are in a public place.

"We call for an urgent tightening of the conditions under which psychiatric patients who, without treatment, might pose a risk to themselves or others, are rehabilitated into the community."

Residents living near the hospital have also called for increased transparency from the trust, and have even suggested a warning siren for highly dangerous escapees. Sheila Macleod, of Hardy Way, Enfield, said: "There is such a lack of information as to the type of patients cared for.

"The trust says public safety is paramount, but that is a load of rubbish."

Kathleen Maynes, also of Hardy Way, added: "Living in a small cul-de-sac opposite the hospital side entrance, we feel very vulnerable when these incidents happen the first we ever hear of escapes is when police helicopters hover over our gardens and police dog handlers swarm over our fences.

"We are all very angry and fearful about the situation."

The disappearance of Mr Studders is the third incident of its kind in the last 12 months. Schizophrenic patient 64-year-old Pavlos Takoushis also escaped in January 2003. He later committed suicide.

John Newbury-Helps, chief executive of the Enfield, Barnet and Haringey Mental Health Trust, said that, unlike facilities such as Broadmoor which has a warning siren, Chase Farm is a medium security hospital.

He added: "We recognise that the public have anxieties regarding these issues. We would like to reassure them we are doing all we can to learn any lessons from the recent circumstances and regard the safety of our patients and the public as paramount."