The economic and security benefits of a closer relationship with the EU are “simply too big to ignore”, Keir Starmer has told parliament as the British government prepares for more rapid alignment with European rules.

Updating MPs on the Iran conflict and his visit to the Gulf last week, the prime minister was explicit about what he argued was the need for renewed ties with Europe given the chaotic global situation and Donald Trump’s unpredictable US administration.

The Guardian revealed that ministers were planning to use so-called Henry VIII powers to dynamically align with EU rules by default, including the adoption of changed EU single market rules without full parliamentary scrutiny each time.

Setting out what he said were the lessons of the Iran crisis, Starmer said that after Brexit, Covid and the Ukraine war the idea of a global shock to UK living standards was no longer “a novel experience”, and that lessons should be learned.

This time, he argued, the response “must and will be different to reflect the changing world that we live in”, saying this included efforts to reduce energy bills.

He went on: “Looking forward, it also means a closer economic relationship with our European allies, because Brexit did deep damage to the economy, and the opportunities we now have to strengthen our security and cut the cost of living are simply too big to ignore.”

In his Commons statement, Starmer condemned as “wrong” continued Israeli strikes on Lebanon after a ceasefire was agreed over the USand Israelwar on Iran, while warning that Iran’s blockading of the stait of Hormuz was “causing untold economic damage”.

The UK would play no part in planned attempts by the US to mount a counter-blockade of the strait, he added.

Questioned by MPs about Trump’s pre-ceasefire threat last week that that Iran’s “whole civilisation will die” if Tehran did not comply with his demands, Starmer condemned the US president’s words.

“Could I really be clear with this house that that was wrong,” he said. “A threat to Iranian civilians in that way is wrong. These are civilians, let’s remember, who suffered immeasurable harm by the regime in Iran for many, many, long years.”

Starmer’s very clear call for closer EU links has opened up a greater divide with the Conservatives and Reform UK, who have both condemned the plans for alignment-by-default, details of which will come in a bill to be presented in next month’s King’s speech.

The Conservatives’ shadow business secretary, Andrew Griffith, said Starmer was unable to accept the decision of the 2016 referendum, with parliament “reduced to a spectator while Brussels sets the terms”.

Speaking at a press conference in Westminster, Nigel Farage, the Reform UK leader, said Starmer wanted to create closer links with “a declining part of the global economy”.

Asked about the plans, Farage said: “To tie ourselves ever closer to it makes no sense in economic terms. In democratic terms, it is a total betrayal of the Brexit vote 10 years ago, and it is also a complete breach of the Labour manifesto and a further devaluation of parliament.”

But speaking to the BBC on Monday morning, Starmer argued that opponents of the plans needed to recognise that the world had changed.

“I think it’s also a sense, 10 years on from the Brexit referendum, that we’ve got to look forward now, not backwards,” the prime minister said. “Let’s not just have all the old arguments of the last decade.

“Let’s go forward and recognise that a stronger, closer relationship with Europe is in the UK’s best interest, particularly in a world that is as volatile as it is.”

Under the proposed bill, ministers are planning to argue that the move will add billions to the UK economy, temper the cost of the Iran conflict and boost sluggish productivity.

The Guardian understands that if the bill – expected to be introduced before the summer – is passed, negotiators could seek to adopt EU rules on everything from cars to farming using secondary legislation.

Parliament can either approve or reject secondary legislation but cannot amend it, which would probably mean MPs will “rubber-stamp” new deals rather than debate and vote on every one. Any blocking votes would be likely to cause issues with the EU, and could spark retaliatory action. A source said: “We are clear parliament will have a role for new deals and on new EU laws applying under those deals.”