Mr Robertson claimed the Conservatives were scared of losing an independence vote as he attacked Theresa May’s decision to block a poll.
“Let there be no doubt, Scotland will have its referendum and the people of this country will have their choice. They will not be denied their say,” Mr Robertson said.
“Scotland’s referendum is going to happen and no UK Prime Minister should dare stand in the way of Scottish democracy. At this conference we will show the trust we place in the people of Scotland.”
Mr Robertson’s remarks will fuel speculation that the SNP intend to hold their own advisory referendum without Westminster permission.
Despite Mr Robertson’s rhetoric, sources close to Nicola Sturgeon have indicated the First Minister is not inclined to hold an illegal vote.
Earlier Deputy First Minister John Swinney warned that Mrs May would be “ill advised” to stand in the way of a second vote when he was interviewed on BBC’s Today Programme.
Mr Robertson criticised Mrs May’s refusal to allow a referendum. The Prime Minister has said “now is not the time” for another vote.
The SNP Westminster leader said: “It is clear from the PM’s panicked repsonse to the Scottish Government’s decision to rightly give people in Scotland a choice over Scotland’s future, that the Tories are simpjly scared of the people’s choice.
“The Tories argument is not about process it is about their desperate desire to prevent anyone having the chance to reject the hard right Brexit that they are so wedded to.
“We face the real prospect of right wing Tory governments until at least 2030 and being dragged out of the EU and single market with all the damage to our economy and society that will cause.”
“If the prime Minister refuses to engage on the terms of a referendum before Brexit takes place then she is effectively tryingto block the people of Scotland having a choice over their fugture. That would be a democratic outrage.
“If Scotland can be ignored on an issue as important as our membership of the EU and the single market then it is clear that our voice and our interests can be ignored at any time and on any issue.”
He added: “So when the terms of Brexit are known - and not before - we will give the people the choice over the direction Scotland should take - before it is too late to change course.”