Lambsdorff, a German Liberal lawmaker, told the Deutschlandfunk station that he hoped British voters would decide to stay in the EU in a referendum on June 23. But he said the EU would survive, whatever the outcome, Reuters reported on Sunday.
"A European Union without Germany or France is completely unimaginable, but we had a European Union without Britain at the very beginning," he said in an interview. "It won't be the end of 'Project Europe', as some are describing it."
Group of Seven leaders and many others have warned that a British vote to leave the EU would be a serious risk to global economic growth.
Lambsdorff said the EU would have to reform, no matter what happened. In a deal struck with fellow leaders in February, Prime Minister David Cameron won the right for Britain to opt out of the group's principle of "ever closer union" and for national parliaments, working in concert, to block some EU legislative proposals.
If the UK left, EU rules would have to change to adjust the voting structure. In either event, Lambsdorff said, it would be critical to improve the organization’s ability to act as one body, and might also make sense to have a two-tier European system with different members moving at different paces.