Britain unveiled a tough negotiating mandate for talks with the European Union on Thursday, underlining its desire for future economic and political independence that pits London on a collision course with Brussels.

After leaving the EU last month, Britain has until the end of the year to negotiate a trade deal and agreements on everything from fishing to transport, ending more than 40 years of close political and economic relations.

Having accepted that by leaving the EU's customs union and single market British businesses will encounter new "frictions" in trade with the bloc, Britain has made its stance clear - regained sovereignty will trump the economy.

The two sides have until June to get what London's negotiating team called "the broad outline of an agreement" to be finalised by September, otherwise Britain would head for an Australian-style agreement, a looser trading arrangement.