The Welsh Government would not back any Brexit deal negotiated by Jeremy Corbyn if he were prime minister, its Brexit minister has said.
Jeremy Miles said the Cardiff administration would campaign for remain in any Labour-led referendum.
Cardiff North MP Anna McMorrin added that UK Labour needed to “catch up with Wales” and back remain.
Their comments come as the Labour Party votes on its Brexit stance at its annual conference in Brighton.
Mr Miles told BBC Wales Live remaining in the EU was “better than any version of leaving the European Union”.
He was asked by presenter Bethan Rhys Roberts: “Let’s be clear, if Jeremy Corbyn were to be in Downing Street and were to negotiate a Canada-plus or a Norway-plus deal, the perfect deal for you, you would campaign to remain?”
Mr Miles replied: “We have been clear than remain is better than any version of leaving the European Union. We would campaign to remain.”
Speaking to BBC Wales at the Labour Party conference in Brighton, Ms McMorrin said: “We’ve got a very clear policy in Wales. Welsh Labour has been very, very clear, in saying that we need to put any decision to the people for a final say.
“In any referendum we will campaign to remain. That’s what I’ve been saying for many, many years now since the referendum, and that’s what I think England and essentially UK Labour need to catch up with Wales.”
David Davies, the Conservative MP for Monmouth and a Brexit supporter, told the programme the position was “just extraordinary”.
He said: “Regardless of what Welsh Labour want, the UK Labour Party must have enjoyed the last four years so much they want to go off and do the whole thing all over again.
“Start again with a negotiation with Brussels and then come back with a referendum but this time in a referendum some of them are going to be campaigning against their own deal while their leader sits on the fence on the most important issue that’s faced this country for decades.”
On Sunday, First Minister Mark Drakeford reaffirmed his commitment to campaigning for remaining in the EU in the event of a second referendum on Brexit or a general election, when he addressed the Labour conference.
This stance has put him at odds with the UK Labour stance on Brexit. Mr Corbyn has said Labour will deliver the Brexit option people choose in a referendum if the party wins power.
The Labour Party will vote on its Brexit stance at its annual conference in Brighton on Monday.