The confidential health records of half a million British volunteers have been offered for sale on Chinese website Alibaba, the UK government has confirmed. The data, belonging to participants in the UK Biobank project, was found for sale on three separate listings last week. The records have now been removed and it is not believed any sales were made. The latest breach comes after the Guardian revealed last month that UK Biobank data had been exposed online dozens of times and will raise further questions about whether security has been…