British prime minister frontrunner vows to limit immigration

The favourite to become Britain's next prime minister vowed on Sunday to push for an EU trade deal that limits immigration, as a law firm warned Brexit needed parliament's backing to begin.

The shock June 23 vote caused upheaval in British politics and financial markets, leaving lawmakers at odds over what negotiating position to take and when to begin the official exit procedure from the European Union.

Though she campaigned for the "Remain" side, interior minister and Conservative leadership frontrunner Theresa May has said she will honour the result of the referendum and has ruled out holding a general election before 2020.

German Chancellor Angela Merkel has insisted a British trade deal would have to include freedom of movement.