Drug-resistant cases of tuberculosis (TB) are on the rise in the UK, figures suggest.
The number of cases of the infectious disease which could not be treated by common methods has risen by 26%, according to the Health Protection Agency (HPA).
In 2010, there were 342 cases which could not be treated by traditional antibiotics, while in 2011, this figure rose to 431.
Overall, 8,963 new cases of TB were reported to the HPA in 2011, up from 8,410 cases in 2010.
Professor Ibrahim Abubakar, head of TB surveillance at the HPA, said: "Although we are disappointed that there has been an increase in new TB diagnoses in the past year, we are pleased that TB cases overall have been stabilising since 2005, with around 8,500 to 9,000 new diagnoses each year.
"However, the increase in drug-resistant cases remains a concern and a challenge to our efforts to control TB in the UK.
"TB continues to disproportionately affect those in hard to reach and vulnerable groups, particularly migrants.
"In order to reduce TB cases in the future, it's very important that health commissioners, especially in parts of the country with the highest rates of TB, prioritise the delivery of appropriate clinical and public health TB services."
TB is a bacterial infection which is spread by inhaling drops of saliva when an infected person coughs, speaks or sneezes.
It mainly affects the lungs but can spread to other parts of the body including the bones, skin and nervous system.
Typical symptoms of TB include a persistent cough, chest pain, weight loss and night sweats.
* The data is being presented at a meeting of the International Union against Tuberculosis and Lung Disease at Imperial College London later this week.