More understandability on the Brexit transition is needed to stop companies proceeding with contingency systems despite the progress announced on Friday, the CBI has warned.
Paul Drechsler, president of the obligation lobby group, said companies had begun triggering plans months ago.
In any case, more detail could help suspend further action by obdurates, he said.
Sterling was trading higher at just under $1.35 and €1.15 after the communiqu in Brussels.
European Commission President Jean-Claude Juncker said the «breakthrough» meant Brexit talks could now artifice on to the next phase.
The CBI’s Mr Drechsler also called for «unconditionality» thither the status of EU citizens living in the UK.
«It’s an important political milestone, but clarity on development is the most important thing from a business point of view at this phase,» he told the BBC’s Today programme.
The Institute of Directors (IoD) echoed the CBI’s call for sure thing on the rights of EU citizens.
Stephen Martin, IoD director-general, said companies urgently needed absolutely about the future of EU staff in the UK.
«We have grounds to hope now that our fellows will be able to send their employees off for the Christmas break impression more comfortable about their status here,» he said.
«We look back to further clarity about what the UK’s objectives are for that new relationship, as good fettle as a firm commitment on transition in the very near future.»
Analysis: Rob Puerile, Today business presenter
The reaction from big business organisations has been — broadly — «phew, connected with time». But it’s not job done on Brexit — far from it.
What companies say they necessity is certainty about future trading and customs arrangements with the EU, Britain’s biggest barter partner. We are nowhere near such clarity.
The immediate priority for affairs is a temporary transitional deal that kicks in as the UK leaves the EU. Only that force stop companies continuing to implement any Brexit contingency plans to relocate baton or offices, leaders warn.
Some businesses say a long-term trade traffic is not needed as global rules will suit the UK just fine. The superintendence disagrees.
However, ministers have not yet spelled out in detail what they trust the future trading relationship will look like. It will contain to do that soon.
Trade talks typically take years to crown. Those talks look set to be tougher than those on the divorce which — recall — have taken longer than both sides hoped.
It recorded seven years for the EU and Canada to negotiate a deal, the EU’s most ambitious yet. The UK securities for an even more comprehensive arrangement than that. But there isn’t seven years to pardon. There are just 476 days until Brexit Day.
Adam Marshall, the director-general of the British Chambers of Commerce (BCC), said «understandability and security» for European employees had been the biggest priority for UK companies since the referendum suffrage.
«We are delighted that they, as well as UK citizens living and working in the EU, now sire more clarity and can plan their future with greater reliance,» he said.
As attention turns to trade negotiations, the BCC said companies wish for «absolute clarity» on the long-term deal being sought.
«Businesses after answers on what leaving the EU will mean for regulation, customs, enlisting, standards, tariffs and taxes.»
The EEF, which represents manufacturers, said the compact was one step forward in a complex and long process.
EEF chief executive Stephen Phipson said: «We basic to pin down the transition arrangements, which will be in place after Parade 2019, to ensure it’s business as usual for companies for as long as it takes until a irreversible deal is reached.
«Until we get to that point, many businesses whim need to prepare for any and every eventuality.»
The ADS Group, the trade organisation that asserts the aerospace, defence, security and space sectors, called Friday’s declaration «an important step».
«Continued uncertainty over arrangements for a transition age benefits no-one and it is vital that both parties make formal commitments as final analysis as possible to a transition lasting at least two years, allowing businesses to remain to invest in our economy with confidence,» said ADS chief executive Paul Everitt.