Media playback is unsupported on your device Media caption The machines have helped cut the number of infections by half

A fleet of Dalek-style robots are deep-cleaning the hospital wards of north Wales after an outbreak of Clostridium difficile (C. diff).

The robots are part of a structured cleaning plan by Betsi Cadwaladr health board in a bid to reduce the number of infections at its hospitals.

It apologised in 2013 for their failure to control C. diff at Glan Clwyd hospital in Bodelwyddan.

A follow-up report says the number of infections is "still too high".

The report said hospitals in north Wales are making progress in reducing infections but more work is needed.

It looked at changes in management, organisation and practice which have been put in place.

Cleaning staff have changed the products they use and their techniques.

And the deep cleaning robots are now part of a coordinated programme to combat infection.

"It isn't rocket science, but it is about getting everything consistently in place for every patient every time," said Tracey Cooper, assistant director of nursing for infection prevention. "I think as a health board we've made tremendous progress since this time last year.

"If you look at the numbers of infections, they've approximately halved from where they were. But that's not good enough."

Exterminating dirt with 'Daleks'

Image caption Deep cleaning machines known as "Daleks" are now used to clean wards

BBC Wales was given access behind the scenes at Ysbyty Gwynedd hospital in Bangor to see the cleaning techniques used.

Hydrogen peroxide vaporiser machines are now in use at all three of the health board's main hospitals at Wrexham, Bodelwyddan and Bangor.

Known to staff as "Daleks" because they look similar to the robots in the TV series Doctor Who, they work by filling an empty and sealed ward with hydrogen peroxide vapour to exterminate any infections that remain after cleaning.

Prof Brian Duerden, emeritus professor of medical microbiology at Cardiff University, was asked to lead the independent expert review of infection controls, and to recommend improvements.

He found there had been "significant progress" since 2013 but added "this is not to say that all is in place and that the job is done".

He said the healthcare associated infections (HCAI) rates are "still too high when compared with elsewhere in Wales and comparators in England".

He added: "The reduction in numbers needed to reach the Welsh government targets is still a very significant challenge."

Hospital managers will meet on Tuesday to discuss the findings and consider what more needs to be done in the fight against bugs such as C. diff and MRSA.