Keir Starmer said Britain will seek closer ties with the European Union and other European allies in response to the Iran war, arguing that the country’s long-term national interest now requires deeper co-operation on security and the economy as global instability intensifies.

At a Downing Street press conference on Wednesday, the prime minister linked the shift directly to the fallout from the conflict, which has pushed up fuel prices, added to pressure on mortgages and disrupted energy and trade routes. He said Britain needed a stronger relationship with Europe in a more volatile world, while insisting Labour’s Brexit red lines remained unchanged.

Starmer said the government would not seek to rejoin the single market or a customs union, and would not restore freedom of movement. But he said those limits still left room for much closer co-operation with the EU than exists now.

He signalled that a second UK-EU summit later this year would be used to pursue a more ambitious package of economic and security measures, rather than simply reviewing the work already under way. Summer talks are expected to cover areas including food standards, emissions policy and a limited youth mobility arrangement.

The prime minister said Britain’s ties with Europe should be strengthened on defence, intelligence, energy security and trade, presenting the move as a practical response to the pressures created by the war rather than a reversal of Brexit.

He also said Brexit had done “deep damage” to the British economy and argued that the opportunities to improve security and ease pressure on living costs through closer co-operation with Europe were too important to ignore.

Starmer sought to cast the policy as a rebalancing rather than a choice between allies. He said he would not choose between Washington and Brussels, arguing that a stronger European pillar on defence and security would reinforce, not weaken, the UK’s relationship with the United States.

On the conflict itself, Starmer repeated that it was “not our war” and said Britain would not be drawn into combat operations. He said the government’s immediate focus was on de-escalation, diplomacy and restoring freedom of navigation through the Strait of Hormuz, through which about a fifth of global oil and liquefied natural gas supplies normally pass.

He announced that Foreign Secretary Yvette Cooper would host a 35-nation meeting later this week aimed at finding diplomatic and political ways to reopen the strait and protect shipping. The talks are expected to involve G7 and European partners and will examine how to safeguard seafarers and resume the flow of energy supplies. Allied military planners are also expected to consider options for securing the route once the fighting subsides.

The prime minister said Britain was “well placed to weather the storm”, but warned that the coming weeks would not be easy.

The domestic impact of the crisis is already being felt. RAC figures published on Wednesday showed diesel prices had risen from 142.4p a litre on 28 February to 184.2p, an increase of 29%, while petrol had climbed from 132.8p to 153.7p, up 16%.

The Bank of England also warned that around 1.3 million additional UK households were now facing higher mortgage costs because of market turmoil linked to the conflict, and said the broader economic outlook had deteriorated as borrowing costs rose and growth weakened.

There have also been warnings from the aviation sector that prolonged disruption to shipping routes could begin to squeeze jet fuel supplies in Europe in the coming weeks.

Starmer’s intervention comes amid growing strain in relations between London and Washington after he refused to commit Britain more directly to the conflict. The Trump administration has publicly pressed allies to do more, while the US president has also cast doubt on the value of NATO and suggested countries that do not back the war effort should not rely on American help to deal with energy shortages.

The prime minister used Wednesday’s press conference to restate Britain’s commitment to NATO, describing it as the most effective military alliance in history and saying the UK remained fully committed to it.

Earlier, Chancellor Rachel Reeves said she was “angry” that Donald Trump had gone to war in the Middle East without a clear plan for bringing it to an end. She also rejected suggestions that higher oil and gas prices could produce a windfall for the Treasury, saying any gains would be outweighed by weaker growth, higher borrowing costs and a broader hit to household finances.

The government’s position was welcomed by pro-European groups and unions, which argued that the war had exposed the need for closer co-operation with Britain’s nearest neighbours.

Naomi Smith, chief executive of Best for Britain, said it was “entirely right” for Starmer to seek much closer ties with European allies in response to the conflict and its economic effects, while pressing ministers to go further and faster in rebuilding the relationship.

TUC general secretary Paul Nowak said the government should be ready to protect low-income households if the crisis deepened, and said stronger trading ties with the EU made sense at a time when the US was showing itself to be an unreliable global partner.

The Conservatives accused Starmer of using the crisis to reopen old Brexit arguments. Shadow foreign secretary Priti Patel said the prime minister was trying to blame Brexit for a cost-of-living squeeze she said was rooted in Labour’s own economic choices, including tax rises and what she described as “net-zero zealotry”.

No 10 is expected to set out more detail in the coming weeks on what it wants from the next phase of UK-EU talks. For now, Starmer’s comments amount to his clearest statement yet that the Iran war is reshaping Britain’s foreign and economic policy, pushing his government towards a closer European partnership while trying to preserve the UK’s wider alliance with Washington.