The UK would face "disaster" if it stayed in the EU's customs union after Brexit, Labour's shadow international trade secretary said on Monday 24 July.
"If you do what Norway does, what happens is the very reason that most people who voted leave – namely to regain sovereignty, to regain control of our borders, not to pay money into the European budget – are not achieved," Barry Gardiner told BBC Radio 4's Westminster Hour.
"To adopt the Norwegian situation would be to become a vassal state because you actually end up paying money into the EU budget, but you have less control over the regulations than you do now with a seat round the table."
The comments, issued just a day after after Labour leader Jeremy Corbyn claimed that his party hadn't "jumped on either side of that fence" in the customs union debate, triggered a fresh row.
Chuka Umunna, the Open Britain campaigner and member of the All Party Parliamentary Group (APPG) on EU relations, warned that Labour's stance would be indistinguishable from the government's.
Theresa May, like Gardiner, wants to split from the single-market and customs union so that Britain can broker its own free trade agreements with non-EU nations.
"We need clear red water between [Labour's] position on Brexit, and that of Ukip and the Tories. It's what our members and supporters expect," Umunna said. "Taking Single Market and Customs Union membership off the table in the Brexit talks is the Tory position, it should not be Labour's."
Labour's 2017 general election manifesto, meanwhile, called for a "jobs first" Brexit.
"We will scrap the Conservatives' Brexit White Paper and replace it with fresh negotiating priorities that have a strong emphasis on retaining the benefits of the single market and the customs union – which are essential for maintaining industries, jobs and businesses in Britain. Labour will always put jobs and the economy first," the document said.
Elsewhere, Shadow Brexit Secretary Sir Keir Starmer is reportedly joining Mishcon de Reya as a legal adviser. The firm was behind Gina Miller's successful court bid to allow MPs and peers to vote on triggering Article 50 of the Lisbon Treaty, the official mechanism to split from the EU.
Starmer was paid £18,000 for four month's worth of legal advice in 2016, according to the House of Commons' register of members' interests.