Clifford Chance senior partner tells PM Cameron to stay in the EU

Sweeting is one of nine high-profile signatories to an open letter published in the Financial Times that has come as the Obama administration in the US has warned Prime Minister David Cameron that the UK should stay in the European Union.

In the letter Sweeting, along with the other signatories, accepts that there is a need for EU reform, but warns that a wholesale renegotiation of EU membership has significant risks for the UK.

The letter states: “We must be very careful not to call for a wholesale renegotiation of our EU membership, which would almost certainly be rejected.

“To call for such a move in these circumstances would be to put our membership of the EU at risk and create damaging uncertainty for British business, which are the last things the Prime Minister would want to do. We need a strong reformed EU with Britain at the heart of it.”

Nevertheless, they said there was room for some reforms “not least of the working time directive and the antiquated EU budget, and completion of the single market in services such as digital, telecoms and energy”.

The Prime Minster caused controversy on Sunday when he said he would block EU treaty changes aimed at making the euro more effective unless he is allowed to repatriate powers to the UK. He is due to set out his position on Europe in a landmark speech later this month.

Business leaders are becoming increasingly nervous that political manoeuvres could cause upset for business dealings with their European counterparts.

The letter continues: “The EU remains home to half our exports and is the most powerful trading bloc in the world. Other EU member states are the main source and destination of foreign direct investment into and from the UK, accounting for about half of our investment.”

The remaining signatories were: Business for New Europe chair Roland Rudd; Corsair Capital chair Mervyn Davies; London Stock Exchange chair Chris Gibson-Smith; TheCityUK chair Gerry Grimstone; Rio Tinto chair Jan du Plessis; BT chair Sir Michael Rake; and WPP chief executive Sir Martin Sorrell.