British UN Ambassador John Sawers | Hiroko Masuike/Getty Images Brexit might not happen, says former British spy chief John Sawers said Brexit would impact the UK’s ability to deploy ‘coercive foreign policy strategies.’

Former MI6 chief John Sawers suggested Thursday that Brexit may still not happen, while also warning that the U.K.'s divorce from the EU would have an impact on the country's diplomatic clout.

"The vehicle through which we have conducted sanctions regimes for the last 20 or so years has been the European Union," Sawers told a House of Lords committee on EU sanctions, according to The Telegraph.

"So clearly, the Brexit — assuming it goes ahead — will have an impact on how we take part in coercive foreign policy strategies and it's not just the compiling of sanctions regimes, it's our whole approach to how do we deal with difficult countries like Russia, Iran or North Korea, or how we deal with terrorist organizations like al-Qaeda or ISIS,” he added.

"Sanctions tend to be part of a wider strategy and we need to think about how the United Kingdom is going to play a role once the centerpiece of our policy coordination and application of policy and sanctions is no longer available to us."

Reactions from Brexiteers and Remainers were quick to follow, with pro-EU group Open Britain calling on hard Brexiteers to rethink their strategy.

“If anyone would know about how Brexit could impact on our security and foreign policy, it is the former head of MI6," Open Britain supporter and Labour MP Chris Bryant said in a statement. "His remarks today blow apart the complacent assumption of the Brextremists that our influence in the world will be unaffected by leaving the EU ... Hard Brexiters should think long and hard before they embark on a no deal strategy.”

In response to Sawers' statement, Conservative MP Jacob Rees-Mogg told The Sun that the Brexit referendum last year “was a decision made by the British people, not spooks.”