UK Labour is directly contradicting Welsh Labour on Brexit, Lib Dem leader Sir Vince Cable has said.
Visiting Cardiff as part of a tour meeting party members, he said First Minister Carwyn Jones and Labour leader Jeremy Corbyn "are effectively in different parties" on the issue.
Mr Jones has said there is no need to leave the EU single market, while Mr Corbyn said the UK should do so.
Shadow Chancellor John McDonnell has insisted they are "on the same page".
Sir Vince told BBC Wales: "At a UK level Jeremy Corbyn is working hands and glove with the May government in order to secure a hard Brexit, not just a Brexit but leaving the customs union, single market, all of those very good things.
"I'm aware that the Welsh Labour party is singing from a completely different tune but that is seriously dissonant. People are looking for some consistency.
"They know that the Liberal Democrats in Wales and at a UK level are completely clear and consistent that our future lies with Europe and minimising the damage from the Brexit."
He said Welsh Labour's position "may make sense internally within their own group but at a UK level their own party is directly contradicting what they are doing.
"Carwyn Jones can distance himself as far as he likes from Jeremy Corbyn but they are effectively in different parties and I think the public can see through that."
The Welsh Liberal Democrats had campaigned for Remain at the EU referendum, where Wales voted to leave the EU.
The Welsh Liberal Democrats won no seats at the general election in June, losing the Ceredigion seat Mark Williams held to Plaid Cymru's Ben Lake.
Kirsty Williams, AM for Brecon and Radnorshire and Welsh education minister, is currently interim leader of the Welsh Lib Dems as the position can only be taken up by an MP or an AM.
Sir Vince said: "We're naturally very disappointed that we don't have an MP in Wales.
"Mark Williams was a super MP. We've been previously very strong in mid Wales and we had strong strongholds in the south.
"But we'll get back. That's why I'm here," he said.
"We have a strong group on Cardiff council. We've got a foothold in Welsh Government, Kirsty Williams, doing an excellent job, and I think when you have this combination of a very dysfunctional, divisive Tory government and a Labour opposition which flirted with revolutionary socialism, people are looking for common sense solutions and they will get behind."
'New party not needed'
A former chief to staff to Brexit secretary David Davis, James Chapman, claimed on Friday that two cabinet ministers had expressed interest in a new centre party to oppose Brexit.
"I don't think a new party is needed," said Sir Vince, "but we are, as I say, willing to work with people in other parties if that's the way they wish to remain in the short run."
He added: "We're going to have to assemble a coalition of people, Labour, Conservatives, nationalists and ourselves to fight damaging legislation so I am very much into working with other parties.
"But we are a consistent party which is warning of the dangers of Brexit, offering people a choice at the end of process as to whether they want to leave or stay.
"And I think it would be a natural port of call with anyone who is unhappy with the Tories and the Labour party."
A spokesman for the Welsh Labour Government said: "Welsh Labour have been well ahead of the game in terms of shaping the Brexit debate.
"We have consistently argued that protecting jobs and our economy should be the focus of Brexit negotiations and want to ensure that Brexit is a success for our economy and our people."