After talks in The Hague with officials from the European Union police force Europol, Starmer said the Conservative government had “lost control of our borders”, as seen in the large numbers of migrants crossing the Channel to the UK.

“What I am discussing today is a security agreement, sharing of information, operationalising the way we can smash these (trafficking) gangs,” he told reporters, describing as “embarrassing” a charge from the Conservatives that his plan could open the way for 100,000 asylum seekers to enter the UK.

How to tackle illegal migration is set to be a major battleground for both Labour and the Conservatives in a national election expected next year, with many voters angry over the housing of immigrants in costly hotels.

Prime Minister Rishi Sunak has made “stopping the boats” – the arrival of migrants across the Channel – a priority, but his government’s policies, such as sending asylum seekers to Rwanda, have failed to get off the ground.

Starmer, whose party looks set to win the next election according to opinion polls, suggested in the Times newspaper that a Labour government could seek an EU-wide returns agreement for asylum seekers, possibly accepting quotas of migrants in return for sending back people who arrive illegally.

Sunak accused Starmer of opening the door to 100,000 EU migrants every year. “That doesn’t seem like a credible plan to me to stop the boats,” he told reporters.

Before Brexit, the government could ask members to take back people it could prove passed through safe European countries.

In 2019, the UK was able to transfer 263 asylum seekers back to EU countries, according to government data. That is equivalent to fewer than 1% of the just over 45,000 asylum seekers who arrived in the UK on small boats last year.

In a flurry of overseas diplomacy, Starmer will also meet French president Emmanuel Macron next week, when he might also pitch his proposals.