LONDON — British opposition leader Jeremy Corbyn called for “a new comprehensive UK-EU customs union” after Brexit on Monday, a move that could lead to a major parliamentary defeat for Prime Minister Theresa May. “Labour would seek to negotiate a new comprehensive UK-EU customs union to ensure that there are no tariffs with Europe and to help avoid any need whatsoever for a hard border in Northern Ireland,” the Labour leader said. Giving the example of integrated supply chains in the car industry, Corbyn said in a closely-watched speech that it “makes no sense” for Britain to turn its back on “tariff-free trading rules that have served as well. “We are also clear that the option of a new UK customs union with the EU would need to ensure the UK has a say in future trade deals,” Corbyn said, speaking in Coventry, central England. “A new customs arrangement would depend on Britain being able to negotiate agreement of new trade deals in our national interest,” he said. But Corbyn also cautioned that free trade deals with China or the United States would not compensate for loss of trade with the European Union. “Brexit is what we make of it, together,” he said. “Labour’s priority is to get the best Brexit deal for jobs and living standards,” he added. Corbyn also said that he would take a more flexible approach than May to immigration after Brexit, addressing one of the concerns of employers about the risks of leaving the European Union. “We would not do what this government is doing, start from rigid red lines on immigration and then work out what that means for the economy afterwards.” As May tries to strike a divorce deal with the European Union by October, she is facing a rebellion by a small group of pro-Europeans inside her Conservative Party that Labour Party head Corbyn hopes to use to undermine her authority. May has ruled out any customs union with the EU after Brexit because it would prevent Britain from striking new trade deals with fast-growing economies including as China and India. Labour’s Brexit policy chief Keir Starmer said on Sunday his party has agreed that if it wins power it would negotiate to remain permanently in a new customs union with the bloc. Corbyn, however, disappointed some politicians in his party by indicating he, like May, favors taking Britain out of the EU’s single market. “There will be some who will tell you that Brexit is a disaster for this country and some who will tell you that Brexit will create a land of milk and honey. The truth is more down to earth and it’s in our hands: Brexit is what we make of it together,” Corbyn said. “Labour would negotiate a new and strong relationship with the single market that includes full tariff-free access and a floor under existing rights, standards and protections.” Supporters of Brexit have long said striking trade deals around the world would represent one of the big potential gains for Britain from leaving the EU. — Agencies