Reports in the Sunday National suggested the Scottish Government was set to announce the timings and question for a second independence referendum within the next six weeks.
But a Freedom of Information request confirmed to The Scotsman the Bill has not been checked by external or civil service lawyers.
A separate request confirmed the Scottish Government had received legal advice on the general topic of the legality of a second referendum, but officials decided it was not in the public interest to disclose the details and have kept the information secret.
In January the SNP’s president and the Scottish Government’s constitution secretary revealed an 11-point plan setting out a “roadmap to a referendum” that could pave the way for a so-called “wildcat” poll undertaken without the consent of the UK Government.
The plan stated the UK Government would have to agree – in the event of an SNP victory in the Holyrood elections in May – that either the Scottish Parliament could already legislate for a referendum, or agree a new section 30 order as happened in 2014, or block any referendum through the courts.
The proposal also said it would "vigorously oppose” any legal challenge by the UK Government.
However, the response from the Scottish Government suggests officials and ministers have no idea how their draft independence bill would fare in a court battle.
Any legal advice more generally relating to a second referendum was blocked from release by officials.
Reacting, Scottish Conservative shadow constitution secretary Dean Lockhart said it was “deeply concerning” the public were unable to scrutinise advice handed to ministers.
He said: “When all focus should be on the pandemic, the SNP are wasting resource on their reckless plans to inflict a divisive independence referendum within months of the election.
"People across Scotland will rightly view these wrong priorities as dangerous and irresponsible.
"It is also deeply concerning that people aren’t able to see the legal advice and hold these plans up to scrutiny.
"If ministers have been told that there is no legal route, then it is clear that they are willing to stage an illegal referendum which would be utterly reckless."
Scottish Labour’s interim leader Jackie Baillie said: “It comes as no surprise that the SNP Government would fail to seek legal advice on the draft bill for another independence referendum.
“Even on an issue as important as indyref2, the lack of transparency remains a problem, something which is fast becoming the SNP trademark.
“This will cause more division and constitutional argument at a time when the focus of our attention should be on helping Scotland to recover after the pandemic.”
Scottish Liberal Democrat leader Willie Rennie said: “The public will be absolutely baffled that in the middle of a pandemic the SNP are still pushing ahead with an independence bill.
“The SNP should put recovery first, not their misguided obsession with independence.”
A spokesperson for the Scottish Government said: “Publication of the draft Bill is entirely legitimate and we will publish it before the end of this parliamentary term, allowing the people of Scotland to make an informed choice about the country’s future.
“If there is majority support for the Bill in the Scottish Parliament after the next election there could then be no moral or democratic justification whatsoever for any UK government to ignore the rights of the people of Scotland.
“Successive Scottish and UK governments have not disclosed their legal advice other than in the most exceptional circumstances. Legal privilege is inherent to the functioning of good government and the rule of law.
“It’s important that the legal advice which Ministers and their officials receive is full and frank, and not affected by concerns about it subsequently becoming public.
“The Scottish Government takes legal advice on matters of policy when it is appropriate to do so.”