LONDON (Reuters) - Britain cannot tell businesses for certain what its relationship with the European Union will be after Brexit, business secretary Greg Clark said on Wednesday, as ministers met to discuss the government’s approach.

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Businesses want more clarity from the government over what Britain’s trade and customs arrangements with the European Union will look like after it leaves the bloc in 2019 so they can take investment decisions with some certainty.

Prime Minister Theresa May, who is meeting senior ministers to discuss the government’s strategy, is under pressure to offer a detailed vision for future ties with the EU, but she is not expected to come up with a firm decision this week.

In an interview with the BBC, Clark said he could not offer any details of the end-state Britain was seeking while the two sides were still negotiating.

“This is a negotiation which is about to happen. We can’t guarantee an end-state until it has been agreed by both sides,” Clark told BBC radio.

Britain has agreed in principle with the EU to have a status quo transition period, which is expected to be finalised in March.

But a European Commission document showed the EU wants the power to restrict British access to the single market during the transition if it violates agreed rules, prompting an outcry from some Brexit campaigners who said it was an “EU threat”.

Stefaan De Rynck, an aide to EU negotiator Michel Barnier, said the measure was only to be expected. “Foreseeing possibility of sanctions for foul play is of course part of any agreement,” he said on Twitter.

May also called on parliament to disregard the “noise” surrounding the talks to unravel more than 40 years of union, saying she would be robust in her arguments with the EU.

“As I’ve said right from the very beginning ... we will hear all sorts of things being said about positions that are being taken. What matters are the positions that we take in the negotiations,” she said.

But May is under pressure to show more of her hand, with the British Chambers of Commerce saying continued ambiguity would hinder firms as they make investment and hiring decisions.

“Clear UK negotiating objectives are crucial to both business and public confidence,” the BCC said in an open letter to the government.

Many businesses fear Britain could face a disorderly Brexit that would weaken the West, disrupt the peace in Northern Ireland, imperil Britain’s $2.7 trillion (£1.94 trillion) economy and undermine London’s position as the only financial centre to rival New York.