Deputy First Minister Nicola Sturgeon has been singled out for criticism after she gave a speech to about 200 charity representatives last week in which she said the voluntary sector was "picking up the pieces" of the Coalition Government's welfare reforms.
Details of the latent funds come as the Scottish Council for Voluntary Organisations (SCVO) reported that 81% of charities in Scotland expect the sector's financial situation to deteriorate over the next year.
Despite the pressures on charities, the money has yet to be allocated as intended.
It was passed to Scotland as part of a three-year £20m package for the not-for-profit advice sector across the UK.
Holyrood received £1.7m in November 2011, with the same amount allocated in March. A further £1.7m is due next year.
Labour MP Tom Greatrex said: "With increasing pressure on the already tight resources of organisations such as Citizens Advice Scotland, any additional funding would be welcomed. The extra money from the UK Government was announced in November, yet a year later local advice centres aren't feeling the benefit of this.
"It's a bit rich for Nicola Sturgeon to say that voluntary groups and charities are picking up the pieces when it is the SNP in Edinburgh who are depriving them of vital funding."
Mr Greatrex, who represents Rutherglen and Hamilton, added: "The SNP Government must come clean on where the money is. If it is not going to support the important work of organisations like Citizens Advice then SNP ministers should be honest about this."
Finance Secretary John Swinney has already indicated that, given the money was delivered through Barnett consequentials, it is up to Scottish ministers to collectively decide how best to use it in light of the financial position.
The SCVO has urged the Scottish Government to free up the funds to allow the voluntary sector to meet demand.
Citizens Advice Scotland (CAS) contributes £166.2m a year to the Scottish economy, which includes £60m in savings on benefits, NHS spending and homelessness services as a result of the advice it gives, according to a recent report.
A spokesman said: "We are currently in discussion with the Government and other funders about how to make sure the CAB service gets the resources it needs to continue helping our clients."
A Scottish Government spokesman said the vital role played by the third sector within communities was recognised.
He added: "They are close to the harsh reality of these welfare cuts and it is they who so often have to pick up the pieces. That is why we are working in partnership with the sector and local authorities to understand the consequences of these reforms and do what we can to help mitigate their worst impacts."
"The Scottish Government's draft budget for 2013/14 is currently being scrutinised by the committees of the Scottish Parliament. We understand Citizens Advice Scotland is engaged with that process and look forward to receiving the conclusions from the relevant committees in due course."