Britain's decision to leave the EU was the result of a "catfight in the Conservative party that got out of hand", a senior Brexit negotiator has claimed, as he predicted the next generation of Britons would take us back into the bloc.

"There will be a young man or woman who will try again, who will lead Britain again into the European family once again, and a young generation that will see Brexit for what it really is," Guy Verhofstadt, the leader of the EU parliament's Liberal Alliance group, said.

He went on to claim that Brexit was caused by a "catfight in the Conservative party that got out of hand - a loss of time, a waste of energy and a stupidity."

It came as the EU parliament in Strasbourg voted overwhelmingly in favour of the "red lines" on Brexit negotiations as set out by senior Brussels chiefs.

The resolution demands that EU and UK citizens receive "reciprocal treatment," that the final deal should not be a "trade-off" between trade and security, and that the UK pay the costs linked to its withdrawal. It also says that the European Banking Authority and European Medicines Agency should be moved out of London to an EU member state.