Andy Burnham has warned Britain has “lost more than we’ve gained” since Brexit as he prepares for a Brussels summit aimed at cutting trade barriers and boosting economic growth.

Speaking at the Welsh Labour conference on Saturday, Burnham accused the Conservatives of delivering a harder Brexit than voters expected, arguing that closer ties with the European Union could help bring down food prices and support British exporters.

The prime minister will meet European Commission president Ursula von der Leyen and European Council president António Costa on Friday, with negotiations focused on food and farming, emissions trading and youth mobility.

The government hopes the agreements could boost UK GDP by 0.4 per cent, equivalent to around £17bn.

Burnham said a food and farming deal would particularly benefit Welsh lamb and shellfish exporters by reducing the paperwork and border checks imposed after Brexit.

“We must be prepared to make difficult decisions to bring down the cost of living,” he told delegates in Llandudno.

However, he insisted Labour would respect its manifesto commitments, which rule out rejoining the single market, customs union or restoring freedom of movement.

The comments follow his suggestion that Britain could explore a closer long-term relationship with Brussels after the next general election.

Businesses warn over EU reset

The proposed food agreement would bring British regulations into closer alignment with EU standards, removing many of the health certificates and routine checks currently required for agricultural exports.

Ministers estimate the deal could add £5.1bn annually to the UK economy by 2040, although the final terms have yet to be agreed.

But Karen Betts, chief executive of the Food and Drink Federation, warned the changes could place additional pressure on manufacturers already struggling with high energy costs and regulation.

“The sector finds it must rapidly prepare to re-comply with EU food law, in the UK and for exports, under the UK-EU reset about to be signed,” she said.

“This is all diverting precious resources – people and capital – from investing in the manufacturing capacity, efficiency and jobs that underpin our food system’s resilience.”

The negotiations also come amid concerns over proposed EU “Made in Europe” rules, which could restrict subsidies for manufacturers using components produced outside the bloc.

Britain’s automotive industry is particularly exposed, with the proposed measures threatening to disadvantage UK carmakers supplying European markets.

David Bailey, professor of business economics at the University of Birmingham, said securing access to the scheme was “mission-critical” for British manufacturing.

“If Europe introduces a Made in Europe regime that protects its industrial base, the UK needs to be inside it,” he said.

He suggested Britain should consider tariffs on Chinese imports if necessary to secure an agreement with Brussels.

Meanwhile, Tories have criticised the cost of Britain’s planned return to the Erasmus student exchange programme, estimated at £570m next year.