The Labour leader said that, the more the UK and Brussels “share a future together”, the less friction there will be between the two.
The comments, made at a meeting of centre-left leaders in Canada, offer a rare window into opposition thinking on Europe, with the Labour leader previously exercising caution on details of his plans to align Britain more closely with the EU.
Sir Keir said this week that he would push for an improved trading relationship with the EU if Labour were to form the next government. At the same time, France and Germany were said to be pushing plans to offer Britain “associate membership” of the EU.
In footage from a summit in Montreal on Saturday, aired by Sky News, Sir Keir said: "Most of the conflict with the UK being outside of the [EU] arises in so far as the UK wants to diverge and do different things to the rest of our EU partners.
"Obviously the more we share values, the more we share a future together, the less the conflict. And actually different ways of solving problems become available.
“Actually we don’t want to diverge, we don’t want to lower standards, we don’t want to rip up environmental standards, working standards for people that work, food standards and all the rest of it.”
Some Brexiteers have argued that leaving the European Union presents an opportunity to change regulations in areas like product standards or the environment – which were previously agreed in Brussels while Britain was a member of the union.
Other voices, such as trade unions and environmentalists, have said EU rules help keep UK standards high and warned against divergence.
And business have also warned that divergence from the EU might create extra costs.
Under the Brexit deal negotiated by Boris Johnson, the UK's rulebook will gradually diverge from the EU's – though plans to immediately purge the statue books of all EU legislation have been abandoned by Rishi Sunak
Other approaches to Brexit, such as remaining in the single market, would require Britain to remain synced to EU rules – but would lower trade barriers compared to now.
Sir Keir has ruled out rejoining the single market or a customs union, however.
During Brexit talks the EU voiced concerns that the UK could try to undercut European standards by deregulating its economy.
Some divergence has already happened. Earlier this month it was reported that the UK had failed to ban 36 harmful pesticides that are now restricted from use in the EU.
Labour says it will renegotiate a better deal for the UK with the EU. The current agreement, struck by Mr Johnson, comes up for review in 2025 – which could present and opportunity for changes.
A Labour Party spokesperson said: “Labour will seek a better deal for Britain. This does not involve any form of membership.”
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