May builds new-look Brexit cabinet to steer EU divorce

* May stamps authority with sweeping changes

* Finance and justice ministers are top casualties

* Rival Leadsom gets cabinet post

* Bank of England surprises by keeping rates on hold

* French foreign minister says Boris Johnson lied (Adds Johnson, Leadsom, markets)

By William James and Kylie MacLellan

LONDON, July 14 (Reuters) - New Prime Minister Theresa May ruthlessly overhauled the British cabinet on Thursday, sacking a raft of ministers, promoting loyalists and putting supporters of Britain's exit from the European Union firmly in charge of negotiating its terms.

A day after replacing David Cameron, May told the head of the European Commission that Britain needed time to determine its negotiating strategy, brushing off pressure from European leaders to swiftly launch the two-year official exit process.

Her most contentious appointment is Foreign Secretary Boris Johnson, accused by his French counterpart Jean-Marc Ayrault on Thursday of lying to Britons in the run-up to last month's shock referendum vote to leave the 28-nation EU.

Johnson, who during the campaign compared the bloc's aims to those of Hitler and Napoleon, told reporters that despite Brexit, Britain could play an even greater role in Europe.

"There's a massive difference between leaving the EU and our relations with Europe, which if anything I think are going to be intensified," he told reporters.

Three weeks after the referendum, May's new government faces the formidably complex task of extricating Britain from the EU - itself reeling from the shock of Brexit - while trying to protect the economy from feared disruption to confidence, trade and investment.

The Bank of England kept interest rates unchanged on Thursday, wrong-footing many investors who had expected the first cut in more than seven years. But it said it was likely to deliver a stimulus in three weeks' time to support the economy, once it has assessed the fallout from the June 23 vote.

The pound rose on the news but is still down 11 percent since the night of the referendum.

New finance minister Philip Hammond signalled he would take a less aggressive approach to cutting the budget deficit than his predecessor George Osborne, who was dumped on Wednesday, just hours after May stepped into Number 10 Downing Street.

"Markets do need signals of reassurance, they need to know that we will do whatever is necessary to keep the economy on track," Hammond said.

"Of course we've got to reduce the deficit further but looking at how and when and at what pace we do that ... is something that we now need to consider in the light of the new circumstances that the economy is facing."