The former head of the MI6 foreign intelligence service has said Britain could be safer if it votes to leave the European Union.
Prime minister David Cameron has previously said that the UK's national security would be endangered if it votes to leave in the in/out referendum on 23 June.
Writing in Prospect Magazine, Richard Dearlove, who was head of the secret intelligence service from 1999 to 2004, said a Brexit would do little damage to Britain's national security and bring two key benefits.
"Whether one is an enthusiastic European or not, the truth about Brexit from a national security perspective is that the cost to Britain would be low," he wrote.
"Brexit would bring two potentially important security gains: the ability to dump the European Convention on Human Rights...and, more importantly, greater control over immigration from the EU."
Attacks in Brussels on Tuesday inevitably permeated the UK's debate about whether to leave the EU. Supporters of leaving said the bloc's open border policy allowed the killings to take place, but others branded their comments inappropriate.
Dearlove also added that, in terms of national security, Britain gives more than it receives from its European counterparts.
"It is difficult to imagine any of the other EU members ending the relationships they already enjoy with the UK," he said.