The United Kingdom needs to stay in the European Union (EU) as part of a plan to protect its security, two former senior British intelligence officials say.
Lord Evans, the former director-general of the UK's domestic spy agency, MI5, and Sir John Sawers, the former head of the UK's Secret Intelligence Service, known as MI6, made the remarks in an article published by The Sunday Times, saying Brexit could lead to “instability on the Continent”, compounding the current “economic difficulties and the migration crisis".
"If we leave the European Union, we will make it more difficult for our partner countries to hold together the fabric of the European Union, which has kept stability in Europe for the last 60 or 70 years, effectively since the Second World War," they said.
"And so there's a risk of fragmentation, which in turn could lead to instability," they added.
Evans and Sawers also said that modern intelligence work relies on gathering large amounts of data on terrorists and cyber-attackers.
They suggested that if Britain were not in the EU, the country's security forces would be unable to shape the terms for sharing that data.
"Recent attacks in Paris and Brussels show there is further to go, especially in sharing threat intelligence and monitoring movement of suspects. Counterterrorism is a team game and the EU is the best framework available — no country can succeed on its own," they said.
The UK will hold a referendum on June 23 on whether the country should remain a member of the union.
Membership of the European Union has been a controversial issue in the UK since the country joined the then European Economic Community in 1973.
Those in favor of a British withdrawal from the EU argue that outside the bloc, London would be better positioned to conduct its own trade negotiations, better able to control immigration and free from what they believe to be excessive EU regulations and bureaucracy.
Those in favor of remaining in the bloc argue that leaving it would risk the UK's prosperity, diminish its influence over world affairs, and result in trade barriers between the UK and the EU.