Cuts to staff numbers at the Crown Office could "impact on the wider justice system", it has been claimed.

The FDA union said budget cuts to the Crown Office and Procurator Fiscal Service (COPFS) will put prosecutors' health and welfare at risk as they come under increasing pressure.

The budget for the COPFS could be slashed by more than a fifth in real terms between 2009-10 and 2018-19, trade unionists added.

The Procurator Fiscal Society section of the FDA praised the "professionalism and dedication" of its members but said it believes current conditions could "place the health and welfare of prosecutors in jeopardy".

It added: "We cannot see how COPFS can continue to deliver current or improved standards of service with the reduced staffing levels that will be required under the predicted real terms budget cuts that a 'flat cash' settlement would represent.

"We fear that, not only will our members bear the consequences of these increased pressures, but there will inevitably be an impact on the wider justice system and the service provided to the public."

In such circumstances, it said Scottish ministers must either fund COPFS "adequately" or make "difficult decisions" about what the service can be expected to deliver.

The union raised its concerns in a submission to MSPs on Holyrood's justice committee as they prepares to scrutinise the government's draft Budget for the coming year.

A Scottish Government spokesman said COPFS would receive more than £114m in 2018-19, with this representing a real terms increase in spending.

About three-quarters of the cases prosecuted in the high court involve sexual offences - up from 50% two years ago.

The Procurators Fiscal Society of the FDA said these involve "complex investigation" work as well as being "intensive cases which carry significant welfare risks to members involved".

Despite a recent recruitment exercise, the number of prosecutors is almost 6% lower than the record of 558 full-time equivalent staff that was achieved in 2009.

A Scottish Government spokesman said: "The draft Budget will provide over £114m for COPFS in 2018-19 - a real terms increase, including additional funding for staff costs. Staffing decisions within the COPFS are matters for the Crown Agent.

"The Scottish Government has provided additional funding of £2.4m in each year since 2015-16 towards the Courts and Crown Office, in addition to their budget allocations, for extra fiscals, court staff and judiciary to help deal with cases involving domestic abuse and sexual offences.

"This funding has been baselined into the announced budgets for the Courts and Crown Office in 2018-19."

Justice committee convener Margaret Mitchell said MSPs had already warned that "if the COPFS' workload is not addressed there will be gravely adverse consequences for Scotland's prosecution system".

She added: "We do not want there to be a major tragedy or a trial thrown into question before this problem is taken seriously.

"During last year's budget scrutiny, the lord advocate told us he was satisfied the budget was sufficient. However, some of the evidence we have received disputes this, and speaks of a deeply troubling situation.

"It's now crucial that the changes so badly needed are implemented and we look forward to questioning the lord advocate again next week to fully assess the current situation."