The Scottish government will confirm a policy of "no support" for fracking on Thursday, according to information accidentally published online.
Energy minister Paul Wheelhouse is to make a statement at Holyrood which is expected to confirm an effective ban after years of consultations.
But some details have already been published on its website which appears to have been updated prematurely.
The wording suggests an indefinite extension to the existing moratorium.
The alternative would be a legislative ban.
The accidental leak, which has now been removed, was later put down to a "clerical error".
It was published alongside the results of a last minute consultation which was carried out over the summer.
Spoiler alert for tomorrow's fracking statement at Holyrood - someone's already updated the consultations website saying they're going to confirm a "final policy position of no support for unconventional oil and gas" pic.twitter.com/3n5fdhlblK— Philip Sim (@BBCPhilipSim) October 2, 2019
It said: "On 3 October 2019, the Scottish government confirmed its final policy position of no support for unconventional oil and gas (UOG). The responses to this consultation, along with the 2017 Talking "Fracking" consultation and 2019 addendum consultation, were considered in detail by Ministers prior to the finalisation of this policy."
Liberal Democrat energy spokesman Liam McArthur said: "The Scottish government appeared to have confirmed their position on fracking via documents published accidentally online, rather than by announcing it to Parliament more than three years ago when Liberal Democrats pressed them to introduce a ban.
"Across Central Scotland communities sat on or near sites potentially earmarked for fracking have been living in fear of what the Scottish government might decide. By dragging their feet, Ministers have imposed years of uncertainty on those people and their communities."
It is further embarrassment for ministers whose own lawyers told a court that a ban announced in 2017 had been "PR gloss."
Last year, during a legal challenge by the petrochemical giant Ineos, a judge ruled that there was "no prohibition against fracking in force" in Scotland.
But in October 2017 ministers had announced an "effective" ban by indefinitely extending the temporary ban which had been in force since 2015.
The ban uses planning laws to implement the government's policy.
But environmental groups say it risks being overturned by future administrations and have called for legislation to be introduced instead.
Mary Church, from Friends of the Earth Scotland, said: "Ministers must live up their rhetoric and fulfil the promises of two years ago by committing to a full legal ban on fracking that will put this issue to bed once and for all.
"The effective ban announced two years ago has been exposed in court as having no legal force and was described by the Scottish government's own legal team as merely 'the language of a press release'.
"An expert legal opinion from earlier this year shows that not only is it well within the power of the Scottish government to ban fracking, but that legislating would be a far more effective way to stop the industry and defeat any further legal challenges from companies like Ineos who want to frack the central belt.
It has taken four years for the Scottish government to finally make the statement.
Ministers said they would take an "evidence based" approach and ordered six reports into the impact of fracking.
A subsequent consultation exercise showed "overwhelming opposition" to the practice which has caused ground tremors in Lancashire where the UK government has given its backing to the sector.
Last month an earthquake with a magnitude of 2.9 on the Richter scale was recorded near the only active shale gas site in the UK.
A Scottish government spokeswoman said: "Due to a clerical error, a webpage briefly appeared on the Scottish government's website earlier today, which included partial details regarding tomorrow's ministerial statement on the development of Unconventional Oil and Gas in Scotland.
"The error was quickly spotted and the webpage removed."