Jeremy Corbyn has avoided a potentially divisive clash over Brexit at Labour's annual conference after delegates agreed not to push the issue to a vote.
Mr Corbyn is resisting pressure from europhiles in the party, who want him to commit Labour to keeping the UK permanently in the European single market and customs union after Brexit.
In a TV interview as the conference opened in Brighton, he made clear he has deep reservations about the restrictions which single market membership could place on a future Labour government's ability to intervene to support UK industry.
Meanwhile, close Corbyn ally and Labour campaigns chief Andrew Gwynne acknowledged that the issue had the potential to inflict grave damage on the party.
Asked whether wrangling between Remain and Leave supporters could tear Labour apart, he told a fringe meeting hosted by the Huffington Post: "It could, if we're not careful."
Delegates will discuss Brexit on the conference floor on Monday, but there will be no vote.
Local parties and trade unions chose Grenfell Tower, rail services, growth and investment, public sector pay, workers' rights, the NHS, housing and social care as the eight topics for full debate and votes, with Brexit motions failing to win the necessary backing.
As activists gathered in Brighton for the start of Labour's annual conference, 30 senior figures wrote an open letter calling for the party to do whatever it takes to keep Britain in the single market and the customs union.
Shadow Brexit secretary Sir Keir Starmer has previously said that under a Labour government Britain would remain in both for a transitional period of two to four years after the official Brexit date in 2019.
But signatories to the letter published in the Observer, including former shadow cabinet members Chuka Umunna and Heidi Alexander, as well as one of Mr Corbyn's closest allies in his early days as leader, Clive Lewis, said the party should go further to protect jobs and workers' rights.
"At our conference this week, Labour should commit to staying in the single market and customs union - ruling out no options for how to achieve this - and to working with sister parties and others across Europe to improve workers' rights, boost trade union membership and put an end to the exploitation of workers, not freedom of movement," they said.
Speaking to BBC1's Andrew Marr Show, Mr Corbyn said he wanted to ensure "tariff-free access to the European market".
But he added: "I would also say that we need to look very carefully at the terms of our trade relationship, because at the moment we are a part of the single market and that has within it restrictions on state aid and state spending and pressures on it, through the European Union, to privatise rail and other services.
"I think we need to be careful about the powers we need as a national government."
He suggested that EU rules could have prevented him as prime minister from intervening to prop up Britain's steel industry during its recent crisis, and would block a future Labour government from investing in key industries.
Pressed on whether free movement should continue from the EU after Brexit, Mr Corbyn said abuses of the system by rogue employers had to stop but there would still be "a lot" of movement.
"We have to recognise that in the future we are going to need people to work in Europe and people from Europe are going to need to work here," he said.
Conservative chairman Sir Patrick McLoughlin said Mr Corbyn would "backtrack on Brexit" and ordinary working people would pay the price
Liberal Democrat leader Sir Vince Cable said: "The idealistic, pro-EU young people who have rallied behind Corbyn will be mortified to discover that he is working hand in glove with the Conservative Party to promote a 'hard' Brexit."