Health experts are trying to tackle an increase in a highly infectious drug-resistant form of TB which could leave London on the cusp of a TB epidemic.

Scientists have uncovered mutations of the bacteria that are rapidly becoming resistant to all known antibiotics and medications.

During the past year around 3,500 Londoners were diagnosed with the disease, with boroughs like Newham and Ealing experiencing high rates of infection.

Treatment of the multi-drug resistant TB is expensive and can cost between £50,000-£100,000 per patient over two years.

Mobile screening units are being used to locate and isolate carriers of the disease in London but professionals say more needs to be done to tackle TB being imported into the UK from abroad.

Professor Ajit Lalvani, from the National Heart and Lung Institute, says more screening tests are needed to identify latent symptoms of TB that could be brought into the country by immigrants.

Reporter Marc Ashdown looks at what is being done to stop the disease taking hold in the UK.

Read more BBC News, 6 January 2014