The Scottish Labour leader has hit back at suggestions from shadow chancellor John McDonnell that the party would not oppose an independence referendum.
Richard Leonard said he had made clear to Mr McDonnell that there is “no case” for a second referendum.
He also claimed that the majority of people in Scotland were still opposed to one being held.
Mr McDonnell has said a Labour government would not block any request from Holyrood to hold a vote.
His comments – which have been heavily criticised by several senior Scottish Labour figures – contradict the party’s general election manifesto pledge to rule out a referendum, as well as previous public statements by Mr Leonard.
Mr Leonard told BBC Scotland that Labour’s official policy is still to oppose a referendum.
He said he had spoken to Mr McDonnell to “put to him the very clear view that the people of Scotland do not want a second independence referendum and also to remind him that the last independence referendum was supposed to be once in a generation”.
Mr Leonard added: “I was elected 18 months ago directly by the members of the Scottish Labour Party, and one of the parts of the platform I stood on was clear opposition to a second independence referendum.
“So I think it’s pretty clear where I stand, it’s pretty clear where the membership of the Scottish Labour Party stand and that’s the view that we’ll be communicating.
“We will be doing everything we can do to make sure it is in the Labour manifesto for the general election, whenever it comes”.
He also said that, should Labour win a general election, Mr McDonnell would have more pressing priorities to deal with as Chancellor than an independence referendum – such as “resolving austerity, investing in public services and trying to tackle whatever situation we find ourselves in with Brexit”.
An opinion poll published on Monday put support for independence at 52% in Scotland – with 48% opposed – once those who do not know how they would vote were excluded.
But Mr Leonard said his stance on a second referendum would only change if the will of the Scottish people was shown to be “demonstrably” different from 2014, when voters rejected independence by 55% to 45%.
It comes amid speculation that Labour and the SNP are moving towards some form of agreement that would see the parties join forces at Westminster in an attempt to remove Boris Johnson from Downing Street and force a general election.
Former Scottish Labour leader Kezia Dugdale predicted in June that Mr Corbyn would agree to hold an independence referendum if he needed SNP support to form a government.
And Nicola Sturgeon, Scotland’s first minister and the SNP leader, told the Guardian on Tuesday that her party would “always want to be part of a progressive alternative to a Tory government”.
However, Ms Sturgeon also stressed that she was “no great fan of Jeremy Corbyn” and said she “can’t see the SNP going into formal coalition with Labour.”
What did Mr McDonnell say?
Mr McDonnell was being interviewed by LBC broadcaster Iain Dale at the Edinburgh Fringe on Tuesday when he said it would be “for the Scottish Parliament and the Scottish people to decide” whether a referendum should be held before making a formal request for consent to the “English parliament”.
The shadow chancellor went on to say: “We would not block something like that. We would let the Scottish people decide. That’s democracy. There are other views within the party but that’s our view”.
A Labour spokesman later insisted that Mr McDonnell was “clearly not advocating a second independence referendum” and had “made clear the huge benefit a UK Labour government will bring for the people of Scotland”.
The shadow chancellor repeated his comments about not blocking a referendum during a separate Edinburgh Fringe interview on Wednesday – but said the most important thing was getting a Labour government. He also ruled out a formal electoral pact with the SNP.
What other reaction has there been?
Edinburgh South MP Ian Murray told the BBC’s Good Morning Scotland programme that Mr McDonnell’s comments had clearly not been a slip of the tongue.
He said it was “not the first time that senior members of the Labour leadership have come to Scotland and freelanced on this big issue and got it wrong”.
Mr Murray appears to have been referring to comments made in the past by Labour leader Jeremy Corbyn, who has previously said that a referendum would be “absolutely fine” and that he would not rule out granting consent for one to be held if he becomes prime minister.
The MP added: “This is an issue that is in the grasp of the devolved Scottish Labour Party, and that should be the policy that holds”.
Ms Sturgeon has said she wants to hold a referendum on independence within the next two years – but has said formal consent would need to be granted by Westminster before it happens.
She has welcomed Mr McDonnell’s comments on indyref2 as being “basic democracy”.
But Scottish Conservative leader Ruth Davidson claimed that Mr McDonnell was paving the way for a “pact with the SNP in order to parachute Jeremy Corbyn into Number 10”.
She added: “The fact is this – Jeremy Corbyn and John McDonnell would happily sell Scotland down the river if they thought it could give them a sniff of power.
“That is a rank betrayal of the two million Scots – including thousands of Labour voters – who voted to stay part of the UK.”