Boris Johnson has urged European leaders to press ahead with Brexit negotiations as British businesses stressed the need for a transition deal to be agreed as quickly as possible.
The Foreign Secretary said "now is the time to get on with it" after last week's European Council summit agreed to the 27 remaining EU members beginning internal preparations for the next phase of talks, which will cover trading arrangements and a possible transitional phase.
He said that if both sides "think very creatively and very positively" then a deal can benefit people and businesses on both sides of the English Channel.
His comments came after a draft letter intended for Brexit Secretary David Davis showed that five of Britain's biggest business lobby groups have stressed the need for an early deal on post-March 2019 arrangements, warning that firms are preparing to make "serious decisions" with consequences for jobs and investment early next year.
They called for the transition period to match as closely as possible current trading arrangements with the European Union.
With difficulties in negotiations focused on the financial settlement - the so-called divorce bill - Mr Johnson said the UK had made Brussels a "pretty good offer" in Theresa May's major speech in Florence.
At a conference organised by the Chatham House foreign affairs think-tank, Mr Johnson said: "I'm glad that at the Council in Brussels they seemed more positive, frankly, than I thought they were going to be, to judge by some of the anticipatory drum roll of that council.
"They have given a fair wind to the idea of themselves now discussing the new trade deal or however they want to proceed.
"I suggest humbly to our friends and partners in Brussels: Now is the time to get on with it."
He added: "They should grip it, get on with it and start thinking about the future.
"I'm sure that we can both think very creatively and very positively about how to come to arrangements that suit our constituents on both sides of the Channel and benefit businesses not just in this but in Paris and Frankfurt and across the whole of Europe."
Challenged on claims that his interventions on Brexit had undermined the Prime Minister, Mr Johnson said: "The entire British Cabinet is united around every dot, comma, syllable of the Florence speech.
"We think it's an excellent text, and excellent basis on which to proceed and we hope our European friends and partners agree."
Mrs May, who will make a House of Commons statement on last week's European Council summit, has requested a time-limited transition of around two years with the UK and EU trading on broadly similar terms to now and payments to Brussels to fulfil already agreed budget commitments.
But although EU leaders agreed at the summit to begin scoping work on a future relationship, they made clear to the Prime Minister that she must make more concessions on a divorce payment to unlock talks on trade and a transition.
The private letter, which is believed not to have been sent yet, was reportedly signed by the CBI, British Chambers of Commerce, manufacturing trade body EEF, the Institute of Directors and the Federation of Small Businesses.
The letter, originally obtained by Sky News, said: "Agreement (on a transition) is needed as soon as possible, as companies are preparing to make serious decisions at the start of 2018, which will have consequences for jobs and investment in the UK.
"And the details of any transitional arrangement matter: the economic relationship the UK and EU has during this time-limited period must match as close as possible the status quo."
The letter added: "It is vital that companies only have to undertake one adjustment as a result of the UK's withdrawal, not two - and that businesses, the UK Government and authorities in the EU have enough time to make the changes needed to deliver Brexit successfully."