One in three veterans with post-traumatic stress disorder (PTSD) and other mental health problems failed to connect with a counsellor when calling an after-hours helpline, previously hidden government figures have shown.

Key points: Average call wait times jumped to almost three minutes during 2016-17, figures reveal

Average call wait times jumped to almost three minutes during 2016-17, figures reveal Calls to the Veterans Affairs' help service increased 33 per cent in two years

Calls to the Veterans Affairs' help service increased 33 per cent in two years Department of Veterans' Affairs says improvements have been made

The revelation has left a veterans' advocate to question how many former soldiers might have died after not being able to access crisis help.

Figures released under of Freedom of Information showed the counselling run by the Department of Veterans' Affairs (DVA) had an average call "abandonment rate" of more than 35 per cent in 2016-17, up almost 10 per cent on two years earlier.

Abandonment rate is a measure of when a caller hangs up before a counsellor answers the call.

Vietnam veteran and longtime advocate Alan Ashmore said he was "gobsmacked" by the figures.

"One just wonders how many veterans rang the after-hours counselling service with suicidal thoughts, didn't get through and then tragically took their life," he said.

Average wait times for calls also jumped from 67 seconds to almost three minutes — or 174 seconds — during the same period.

The recently released DVA figures also reveal a steady rise in the total number of veterans seeking mental health support over recent years.

In 2014-2015, just over 7,500 calls were made to the counselling service.

That jumped to more than 9,600 calls the following year, and to more than 10,000 calls in 2016-2017.

Improvements being made

The DVA insisted improvements have been made to the "Open Arms — Veterans and Families Counselling" after-hours helpline service in the years since, which had cut call wait times.

"As at 31 December 2018, call wait times have decreased to 59 seconds on average … lower than the 2014-15 wait times," the department told the ABC in a statement.

"Several improvements have been made, including increased staffing, optimised rosters to ensure more staff are available during times of higher call rates, and re-prioritised calls to decrease the length of time callers have to wait for an answer."

Mr Ashmore said he believed the DVA service had improved as a result of new leadership at the department.

"I think it's really important to acknowledge that the attitude of the new DVA secretary [Liz Cosson] and the new team that she's brought in has been a breath of fresh air," he said.

"They're now engaging us whereas before they weren't interested in talking to us".

Veterans wanting after-hours crisis support can call Open Arms on 1800 011 046.