A Labour government will focus on “turning the page on the era of acrimony” with the European Union and restart a “structured dialogue” with the UK’s biggest trading partner, shadow foreign secretary David Lammy said.

He said his party will seek to “improve our trade deal” with the EU, without rejoining the bloc, single market or customs union.

The Labour frontbencher told hundreds of business leaders on Tuesday that the Foreign, Commonwealth and Development Office (FCDO) under a government led by Sir Keir Starmer will put “Britain’s economic future at the heart of our foreign policy choices”.

He criticised the Tory Government for cutting the UK’s diplomatic footprint in fast-growing economies such as India and vowed to “bolster our representation in Europe”.

In a keynote speech to the Trade Unlocked conference in Birmingham, Mr Lammy said: “In government, Labour will give the FCDO a new mission statement with five goals.

“But the top two will be to advance our prosperity and security.

“We will set our world-class network of diplomats a priority task – launching a new economic diplomacy for the modern era.

“Helping to create the conditions for growth.

“Navigating this new geopolitical and geoeconomic context.

“Reducing our vulnerabilities to external pressure.

“Driving forward the energy transition.

“Building partnerships and local capacity.

“Seizing opportunities for Britain to build a modern economy and secure society.”

Mr Lammy said “geography matters” as he pointed to the EU as the UK’s most important economic relationship.

He said the Tories were being “dishonest” by claiming the UK’s accession to the CPTPP, a major Indo-Pacific trade bloc, would make up for lost trade in Europe.

“If you do not think Britain’s relationship with Europe is of fundamental importance to our future, you are living in a fantasy,” he told the conference organised by Best for Britain, an anti-Brexit turned internationalist campaign group.

“The next Labour government will be focussed on what is pragmatic. Turning the page on the era of acrimony that this government has overseen, which has seen trust undermined, cooperation stall and our economy damaged.

“We will seize our opportunity to improve our trade deal with the EU in 2025, when it comes up for review.

“We will go through the trade deal, page by page seeking ways to remove barriers and improve opportunities for business.”

That would include negotiating a veterinary agreement, make it easier for British musicians to tour Europe, and getting scientists access to the EU’s Horizon scheme, he said.

Asked after his speech how Labour would reassure Brexit voters that the referendum will be respected, he said: “the British people understand that our most important trading bloc is the European Union” and that they support a “reset” in the relationship because “they are feeling it in their pockets”.

“Time and time again diplomats are saying to me ‘the UK is not in the room’. We have to get back into the room.

“And therefore the first thing we’ve got to do, and this is another extraordinary thing that’s happened under this Government – there is currently no structured dialogue with the European Union.

“But I can tell you that will change under a Labour government.”

He said Sir Keir, who earlier on Tuesday met European diplomats, is “building a relationship with European leaders”.

But far from seeking to reopen Brexit divisions, the Labour leader “is determined to bring our country back together”, Mr Lammy said.

Diplomats will be tasked with launching “a new economic diplomacy” and help drive prosperity at home, the shadow foreign secretary also said.

“We will deepen our diplomatic ties with countries essential to the supply chains and economies of the industries of the future, including those vital to future supply chains of critical minerals that will power our green prosperity plan.”

Mr Lammy also announced that Labour will put together a new panel of business leaders to give it advice on foreign policy and “ensure that Britain’s businesses make choices with the geopolitical context in mind”.

Conservative Party deputy chairman Lee Anderson said: “Only the Conservative government can be trusted to protect Brexit and deliver on the issues that matter to real people: halving inflation, growing the economy, reducing debt, cutting waiting lists and stopping the boats.”