Labour’s Emily Thornberry has said the party would be “off our bloody rockers” not to seize the chance to remain in the EU via a second referendum, in an interview which put her at odds with comments from Jeremy Corbyn over the weekend.

Speaking in Australia, the shadow foreign secretary said all her meetings in the country had underlined how much better off the UK would be inside the EU.

“People that I’ve spoken to here appreciate that, and I have to say practically all of them … have said if we get an opportunity to remain in the European Union, we should take it. Because if we don’t, we’re off our bloody rockers,” she said.

On Sunday Corbyn said Labour would campaign for a second referendum and to remain in the EU if Johnson was proposing a no-deal Brexit but said the party would “reopen talks with the EU” about a Brexit deal if it won an election.

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Asked personally whether he would prefer to remain in the EU or to leave with a Labour-backed deal, Corbyn declined to make a choice. “Investment, jobs, trade and equality, both in or out of the EU. I want those things,” he said.

“What we proposed was actually a very credible deal. A bespoke customs union with the EU and the trade arrangements would have achieved those things. It didn’t go through parliament, that was the problem.”

Speaking to Sky News Australia’s Graham Richardson, Thornberry said a second referendum should apply to “any deal, or no deal, or whatever this government comes up with”.

She added: “It should be put back to the British people so they can be asked: is this what you voted for? Because if you did, that’s fine. But we don’t think it is what you voted for.

“I’m firmly of the view that Labour’s policy should be that whatever deal a government comes up with – no ifs, no buts, as Boris Johnson says – we should put it back to the people, we should have another referendum, and that Labour should campaign to remain.

“When I’ve been talking to people here in Australia … what’s really come home to me is that one of the reasons for the increased success of the Australian economy … is that you increased your trade with your closest neighbours, and yet in Britain what we’re doing is walking away from our closest neighbours and our biggest trading allies.”

This year Corbyn firmly committed the party to backing a referendum on no deal or a Tory Brexit deal, but went further after the EU elections, saying that if a future Labour government were to negotiate a Brexit deal, that would be put to a referendum too.

The party’s current position is to back remain over no deal or any Tory-brokered deal, but Corbyn has left open the option of Labour backing leave in a referendum on a deal negotiated by a Labour government – or potentially remaining neutral.