Newly released UK figures show that 3250 gay men were diagnosed with HIV in 2012 – more than in any previous year.

Researchers think there are a number of possible explanations for this record number of diagnoses, including increased rates of testing, and ongoing risky sexual behaviour.

Just over a third (34%) of gay men were diagnosed late (defined as having a CD4 cell count below 350), down from 38% in 2010.

There was a fall in the number of new diagnoses involving heterosexual people. Around half of these new diagnoses involved people of black African ethnicity. Among heterosexual people who were born abroad, 48% of new diagnoses involved HIV infections probably acquired in the UK.

The newly released figures also showed that about a fifth of HIV infections in the UK are undiagnosed.

But 97% of people with diagnosed HIV are linked to specialist care, 95% remain in care and 89% of people with a CD4 cell count below 350 are taking HIV treatment.