A Labour government will strengthen diplomatic links with countries critical to Britain’s economic growth – particularly the European Union, shadow foreign secretary David Lammy will say.

Improving relations with the EU is a top priority for Labour, he will say, while accusing the Tories of “living in a fantasy” for failing to recognise its importance.

The Labour frontbencher will tell hundreds of business leaders on Tuesday that the Foreign, Commonwealth and Development Office under a government led by Sir Keir Starmer will focus on a “new economic diplomacy” to help drive prosperity at home.

The department will review where UK diplomats are posted “to deepen our diplomatic ties with countries essential to the supply chains and economies of the industries of the future”, and potentially send more to fast-growing economies such as India.

In a keynote speech to the Trade Unlocked conference in Birmingham, Mr Lammy is expected to say: “The next Labour government 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. Driving forward the energy transition. Building partnerships and local capacity. Seizing the opportunity for Britain to have the highest sustained growth in the G7.”

The Tottenham MP will say that improving Britain’s economic and security relationship with the EU will be key for the next Labour government, which will not, however, rejoin the bloc, single market or customs union.

“Reconnecting Britain must start by reconnecting with our European neighbours,” he will tell the conference organised by Best for Britain, an anti-Brexit turned internationalist campaign group.

“Because the EU are our biggest trading partners. And our allies as we face war on our continent.

“If you do not think Britain’s relationship with Europe is of fundamental importance to our future, you are living in a fantasy.”

Mr Lammy will criticise Rishi Sunak’s Government for doing “zero” in response to other nations’ industrial strategies – including the US Inflation Reduction Act subsidy regime, while highlighting Labour’s green prosperity plan.

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.”