There has been a 57% rise in the number of Afghanistan veterans seeking mental health support, according to new figures.
A total of 358 ex-military personnel sought help from mental health charity Combat Stress last year, compared with 228 in 2012.
The charity's chief executive, Commodore Andrew Cameron, warned that the numbers are likely to increase over the coming years.
He said: "With demand for our services already surging, Combat Stress faces a real challenge in continuing to provide our unique life changing clinical treatment and support services to those who need it.
"We are planning for services at or above the current level for at least the next five years, and we do not expect to see demand for support tail-off in the near future."
The number of Afghanistan veterans needing support has risen sharply in recent years, according to the report. The charity said it currently has 662 in its care. It treats conditions including post traumatic stress disorder, depression and anxiety.
Commodore Cameron said one fifth of all veterans are likely to suffer from mental illness.
"A small yet significant number of veterans who serve in the armed forces each year continue to relive the horrors they experienced on the front line.
"Day in, day out, they battle these hidden psychological wounds, often tearing families apart in the process," he said.
"They have faced unique challenges and require, and deserve, specialist support to help them overcome these challenges."
The statistics were released as Combat Stress celebrates its 95th anniversary. It has supported more than 100,000 veterans since 1919 and is currently helping more than 5,400, which is more than at any time in its history.
Commodore Cameron added: "We cannot allow the ex-service men and women who suffer from the invisible injuries of war to go unnoticed and untreated. This is an unnecessary drain on society and our veterans and families deserve better."