Sir John Sawers, who led MI6 until 2014, said that Britain must not use its security expertise as a bargaining chip in Brexit talks

Britain will face serious security risks if it loses the ability to influence EU rules on data sharing, two former intelligence chiefs have warned.

Robert Hannigan and Sir John Sawers said that a deal must be struck quickly with Brussels to protect the crossborder flow of information used to track terrorists and cyber threats.

Britain may have to accept some European court rulings in return and cannot use its security expertise as a “bargaining chip” in Brexit talks, they said.

Security links in Europe are largely agreed between nations without input from Brussels but EU privacy rules restrict the way in which data can be held and shared between member states. Rulings by the European Court of Justice has also shaped the safeguards, posing an