LONDON Oct 8 (Reuters) - Conflicts in Iraq and Afghanistan may have led to an increase in rates of post-traumatic stress disorder (PTSD), according to new research looking at the mental health of Britain’s soldiers.

The study, published in the British Journal of Psychiatry on Monday, found the overall rate of PTSD among current and ex-serving military personnel was 6 percent in 2014-2016, compared with 4 percent in 2004-2006.

The increase in PTSD rates was mainly seen among ex-serving personnel who had been deployed to Iraq and Afghanistan, the researchers said, with the highest rates among those who had seen active combat.

Among ex-serving personnel who were deployed in a combat role to Iraq or Afghanistan, 17 percent reported symptoms suggesting PTSD, compared to 6 percent of those deployed in a support role such as medical, logistics, signals and aircrew.

The rate of PTSD in the general UK population is around 4 to 5 percent.

The findings are from the third phase of a major cohort study by the Centre for Military Health Research at the Institute of Psychology, Psychiatry & Neuroscience (IoPPN) at King’s College London.

The study has been running since 2003 and is funded by the UK defense ministry. Of 8,093 military personnel included in the third phase of the study, 62 percent had served in Iraq or Afghanistan.

“In previous phases of the study, rates of probable PTSD in our military sample were broadly similar to the general population, but the rates now appear to have risen,” said Nicola Fear, a professor at the IoPPN who co-led the work.

She said more work is needed to find what is behind the rise, but one explanation might be that soldiers who become mentally ill are more likely to leave the military, and more likely to do so after serving in combat, leading to a rise in veterans with PTSD.

Other so-called common mental disorders, such as anxiety and depression, are still far more prevalent in the British military than PTSD, at a collective rate of 22 percent, the researchers said.

But rates of alcohol abuse among military personnel fell to around 10 percent in 2014-16 from 15 percent a decade earlier, the study found.

Simon Wessely, a professor of psychiatry at King’s, said the results “suggest the risk of mental ill health is carried by those who have left the service, and that part of the legacy of conflicts on mental health has taken time to reveal itself”.

But he said it would be wrong to characterize the increase as a “tsunami” or “time bomb” of PTSD in the UK military. He told reporters at a London briefing the findings underline the need to focus on providing and improving mental health services for both serving personnel and veterans.

“We know that more people are accessing services and more people are getting help,” he said. “So that’s good news.”