The survey was carried out for GlaxoSmithKline, which manufactures one form of nicotine replacement therapy.

BBC: NEWS | Health | Mistaken fears over nicotine aids

Dr Robert Anda, of the Centers for Disease Control and Prevention in Atlanta, said nicotine replacement therapy might not be sufficient to help people with long-standing emotional problems.

BBC: Smoking

And although the usual smoking cessation treatments such as nicotine replacement therapy are effective, people with mental health conditions may need higher doses or more intensive support, it said.

BBC: NHS 'ignoring smoking in mental health patients'

She said as well as the shelters, the trust offers staff and patients the chance to take part in smoking cessation sessions, provides special councillors and free nicotine replacement therapy.

BBC: Hospital trust defends smoking shelters