Scottish Labour will decide indyref2 position not new leader, says Richard Leonard
Mr Leonard told the PA news agency he has spoken to UK leadership hopefuls and insisted the Scottish party must make the final call.
It came just days after candidates including Jess Phillips and Lisa Nandy weighed in on Scotland's future within the UK, voicing opposition to a second referendum.
Mr Leonard said: "One of the things that I'm saying to all the leadership candidates in this contest is it's good that they're concentrating a lot of their messages on Scotland - that they understand if Labour is to win again, we have to win in Scotland.
"But I'm getting the message across that in the end, on the Scottish constitutional question, that will be decided by members of the Scottish Labour Party.
"The Scottish Labour Party will be the ones driving that agenda."
But Scottish Labour remains split on the issue, with a number of high-profile figures having spoken in support of a possible second independence referendum while others are against such a move.
'I'm not planning on endorsing a candidate'
Mr Leonard has declined to endorse any of the candidates in the leadership race, instead asking members to vote for who they believe will bring Labour back into Downing Street.
He said: "I'm not planning on endorsing a candidate because I will have to work with whoever is elected.
"There's a very strong field of candidates and there are clear political choices for members of the Labour Party to make.
"Over the course of the next few weeks we'll be having hustings of those leadership and deputy leadership candidates in Scotland and party members will have their chance to cast their vote for the person they think can best oppose Boris Johnson, can best formulate a Labour Party programme, and can best become the next prime minister of this country."
Cut waiting lists
Mr Leonard was speaking at suicide prevention charity Chris's House in Wishaw, where he called for better resourcing of mental health treatment to cut down on waiting times.
He said: "It's about properly resourcing support and making sure that counselling is available when people need it.
"One of the issues around child and adolescent mental health services is that it's got a huge waiting list.
"If someone's got a reason why they need support, they shouldn't have to wait 12 months to get it.
"Allowing people to be on a waiting list for months and months just isn't acceptable.
"People need help when they need it and it's our job as a society to make sure that's there for them."