A drug-free treatment has helped people control their asthma symptoms for up to a year, a study has found.
Over a million children in the UK have asthma
Bronchial thermoplasty uses radio frequency currents to reduce the amount of smooth muscle in the airways, stopping the narrowing seen in asthma.
The research, carried out in hospitals in the UK, Canada, Brazil and Denmark, showed the therapy led to fewer attacks and more days without symptoms.
UK asthma experts said it may be another treatment option in the future.
However, it is likely most people would still need to make some use of their medication.
Asthma affects the small tubes - airways - that carry air in and out of the lungs.
When something triggers asthma, the muscle around the walls of the airways tightens so that the airway becomes narrower. The lining of the airways becomes inflamed and starts to swell and mucus or phlegm can be produced.
These reactions cause the airways to become narrower and irritated, which leads to the symptoms of asthma - such as wheezing, shortness of breath and a tight chest.
More than five million people in the UK are currently being treated for asthma.
Bronchial thermoplasty involves putting a flexible tube through the nose or the mouth in order to target the smooth tissue in the airways.
In the study, the results of which were published in the New England Journal of Medicine, the treatment was given in three one-hour sessions over around nine weeks under a mild anaesthetic.
The researchers, from 11 centres including hospitals in Newcastle, Manchester, Leicester and Glasgow as well as others in Canada, Brazil and Denmark, monitored 112 people with asthma aged 18 to 65 over the course of one year.
All continued to have access to the inhalers and relievers they commonly used to treat their condition.
However, half of the group were also given the bronchial thermoplasty treatment.
These people had an average of 86 more days without asthma symptoms during the year than those who only had access to medication.
The bronchial therapy group also needed to use their inhalers and relievers less, and had better overall control of their asthma.
Dr Gerard Cox, from St Joseph's Healthcare Foundation in Ottawa, Canada, who led the research, said: "These findings are very encouraging and are consistent with earlier trial results on bronchial thermoplasty.
"These results make us hopeful that bronchial thermoplasty may be a new option for asthma patients who have asthma symptoms despite use of current drug therapies."
"Our experience suggests that the bronchial thermoplasty procedure is quite well-tolerated, and it holds considerable promise for patients with asthma."
Victoria King, research development manager at Asthma UK, said the charity had been monitoring research into bronchial thermoplasty with interest.
"As this is an innovative technique we would welcome further research into the long-term effects and benefits for people with asthma.
"Results from these studies provide us with interesting information which enhances our understanding of the mechanisms responsible for the process of asthma and might potentially extend treatment options in the future."