Norbert Roettgen, an influential German politician, has proposed a flexible model of partnership between Britain and the European Union that could put the country on a par with Switzerland, Turkey or Ukraine and sidestep the thorny issue of labour movement.
Britain and its 27 EU partners face the thorny task of hashing out their future relationship after the country voted in June to leave the bloc - a complicated process that will take several years to complete.
One of the key complaints of British voters has been the free access to Britain's labour market enjoyed by EU workers, but Brussels insists that is a core condition for much-cherished access to Europe's single market.
Roettgen - who chairs the German parliament's foreign policy committee and is a senior member of Chancellor Angela Merkel's Christian Democrats - said more flexibility was required, in a telephone interview with dpa.
"Demanding unrestricted labour freedom would stand in the way of a successful and mutually beneficial cooperation between the EU and Britain," Roettgen said, adding that it would be a mistake to take "punitive action" against London.
He proposed a three-tier Europe, which has the eurozone currency area at its core, followed by the remaining EU member states and a third band of partner countries that could include Switzerland, Ukraine, Turkey - and Britain.
The idea is fleshed out in a paper by Roettgen and four others, including the head of a French government-linked policy centre, Jean Pisani-Ferry, published this week by the Bruegel think tank.
The idea could irk Turkey, which is a longstanding candidate for EU membership. Accession talks have dragged, with a recent crackdown by Ankara in the wake of a failed coup raising new questions about the country's suitability for membership.
But Roettgen said the model would offer Turkey a more realistic medium-term perspective.
"An element of honesty could be brought into the relationship," he said.