Keir Starmer will vow to “turn a corner on Brexit” by repairing damage done by Britain’s vote to leave the European Union.
The prime minister will say the UK has a “once in a generation opportunity to reset our relationship with Europe” during talks with German chancellor Olaf Scholz in Berlin.
The pair hope to strike a new bilateral treaty to boost trade, improve defence and security co-operation and tackle illegal immigration.
He will also travel to France later this week as he seeks to “fix the broken relationships left behind by the previous government”.
His comments mark a dramatic change in tone to how the Conservatives dealt with the EU in the wake of the 2016 Brexit vote.
Starmer - who helped lead the campaign for a second EU referendum - will say: “We have a once in a generation opportunity to reset our relationship with Europe and strive for genuine, ambitious partnerships that deliver for the British people.
“We must turn a corner on Brexit and fix the broken relationships left behind by the previous government.
“That work started at the European Political Community meeting last month, and I am determined to continue it, which is why I am visiting Germany and France this week.
“Strengthening our relationship with these countries is crucial, not only in tackling the global problem of illegal migration, but also in boosting economic growth across the continent and crucially in the UK – one of the key missions of my government.”
Germany is Britain’s second largest trading partner, accounting for 8.5% of all UK trade.
Its companies already support more than 330,000 British jobs in places such as Derby, Manchester, Goole and Oxford.
The PM’s negotiating team will spend the next six months agreeing the new treaty, with both sides wanting to agree the new partnership in early 2025.