Divisions have emerged at the top of Labour’s ranks yet again over its Brexit policies as Jeremy Corbyn’s stance on access to the EU’s single market was described as making “no sense at all” by the Welsh First Minister.

The comments came after the Labour leader said over the weekend that Britain would have to leave the market because access was “inextricably linked” to membership of the bloc. Mr Corbyn also said the party had yet to decide is position on a future customs union arrangement.

While Labour’s election manifesto vowed to focus on “retaining the benefits of the single market and customs union”, it was not explicit on whether Britain would actually remain inside the institutions.

But on Monday, the Welsh First Minister Carwyn Jones told the BBC Radio 4’s Today programme there was no need to leave the tariff-free market, adding the UK could have “full and unfettered access” after Brexit.

Citing Norway’s relationship with the EU – Norway is a member of the single market but not the bloc – Labour’s Mr Jones, said: “If we were not in the single market, we would be having a debate about how to access it, not how to leave it.

“There is no need to leave the single market, even as we leave the EU,” he added. “You don’t have to leave the EU and leave one of the world’s biggest markets at the same time. That’s an interpretation that’s been put on the result by the current UK Government and that makes no sense at all.”

The Welsh First Minister added: “For any rational, sane politician to suggest that tariffs are no problem to make it more difficult to sell in that market is crazy.”

Labour would take Britain out of the EU single market, Corbyn says

On Twitter, the senior Labour MP Chuka Umunna added: “Taking single market and customs union membership off the table in the Brexit talks is the Tory position, it should not be Labour’s.”

In a sign of further divisions in the party’s top ranks – this time over the customs unions – Barry Gardiner, the Shadow International Trade Secretary, said on Sunday that remaining in the institution would be a “disaster”.

Mr Gardiner also dismissed the idea of remaining in the single market under a Norwegian-style agreement, saying it would leave the UK like a “vassal state” – paying money to Brussels without any say over the rules.

He told BBC Radio 4’s Westminster Hour: “If you do what Norway does, what happens is the very reasons that most people who voted leave voted to leave – namely to regain sovereignty, to regain control of our borders, not to pay money into the European budget – all are not achieved.

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On the customs union, he continued: “I just want to point out the issues around the customs union, we leave the customs union because only member states of the European Union are members of the customs union.

“Other countries like Turkey have a separate customs union agreement, but the trouble with that is that it gives you an asymmetrical relationship with the third party countries that the EU does a deal with.

“So the EU could do a deal with another country – let’s say America – which we would be bound by in the UK, we would have to accept the liberalisation of our markets, we would have to accept their goods coming into our markets on the terms agreed by Europe, which could be prejudicial to us but we would not have the same access into America’s markets, we would be bound to try and negotiate it. But why would America give us that access when it’s got all the liberalisation of our market that it wants?

“It’s a disaster.”