$58,000 a week spent on Brexit advice

Theresa May's new Brexit department has spent tens of thousands of pounds on legal advice in the eight weeks since its creation, according to official figures.

Britain has yet to formally start talks to withdraw from the European Union, with the Prime Minister and Brexit Secretary David Davis coming under fire for revealing little detail about their plans to MPs.

But the Department for Exiting the European Union said its legal bill has so far reached an estimated PS268,711 ($A464,870) - an average of around PS33,500 ($A57,974) a week.

Officials are still assessing the total amount of taxpayers' cash required for legal advice over the next 12 months when the UK Government is expected to have invoked Article 50 of the Lisbon Treaty, thereby triggering what is predicted to be a complex two-year negotiation process.