Men considered at "high risk" of contracting HIV are not getting tested often enough, according to a new study.

National guidelines suggest gay men and other men who have sex with men should have annual HIV tests and those "at higher risk" should do so every three months but researchers found neither recommendation is being met.

The study of more than 2400 men found fewer than one in five reported having four or more tests in the past two years, while the authors estimated only 54.9% test annually.

Among the HIV testers, more than half - 56.7% - reported that their most recent test was part of a regular sexual health check and more than one third, 35.5%, got tested in response to a perceived risk event.

In total 21.2% of respondents reported having more than four HIV tests in the past two years and 33.7% reported having two to three tests during that time.

Dr Lisa McDaid, the lead author of the study, said: "HIV testing is a core component of current HIV prevention, but despite substantial increases in the uptake of HIV testing in recent years, our results suggest men who have sex with men in the UK do not test frequently enough.

"Furthermore, given that current guidelines suggest individuals at risk of HIV test as frequently as every three months - as well as after a risk event - and that men newly diagnosed with HIV are known to have been less frequent testers, there is a clear need to promote frequent testing as routine and address barriers to frequent testing accordingly.

"Frequent testing will be central to the success of biomedical HIV prevention. HIV self-testing kits are now available in the UK, but it remains to be seen if these can increase testing frequency."

Researchers also noted there was no consensus on which groups were "at risk".

This study, carried out at the Glasgow University's Social and Public Health Sciences Unit, is the first to explore the frequency of HIV testing among men who have sex with men in the UK.

Data was collected from cross-sectional surveys completed by 2409 men in Edinburgh, Glasgow and London in 2011 and a Scotland-wide online survey in 2012/13.

The findings were published in the HIV Medicine journal on Wednesday.