The former British prime minister's pro-Remain comments come shortly after The Telegraph cited US National Security Advisor John Bolton as saying that Washington wanted London to "follow the course of what the people asked for and leave the EU".

Tony Blair, a vocal Remainer who has been open about his support of a second Brexit referendum, has lashed out at Leavers for giving up a "great alliance" with the European Union, slamming it as "an unbelievable act of self-denial".

"Britain has two strong alliances, it has a great alliance with America and it's part of the European Union, which is the biggest political union in the world and largest commercial market in the world. What on Earth would induce you to think that you're going to gain by giving up that relationship. It's an unbelievable act of self-denial. For me, it's just a very simple thing, power is power", he said.

Speaking with interviewer Dan Snow, the former Labour leader and ex-UK prime minister said that "medium-sized" countries should stick together to make sure that giant nations do not "sit on us", and Brexit would prevent Britain from having its interests protected outside the European bloc.

"The plain fact of the matter is for a country like Britain today you need strong alliances to keep your influence strong and your interests protected. The world in the middle of this century is going to have three giants, it's going to have America, China and probably India because these are large population countries. In this world, if the medium-sized countries aren't banding together the giants are going to sit on us", he explained.

Blair continued by saying, "That's just the reality and anyone who's ever dealt with power and sat in a room where there's power understands that when you're with a group of others and you are better operating as one, as a strong collective. It is then that your medium-sized countries bandying together in that European Union are going to sit at the table with the three giants on equal terms. If they're sitting as individuals, they're not sitting at the table. They're sitting on a small table, it is literally as obvious as that".

The former prime minister previously said that the divorce from the EU was, in fact, an "answer to nothing" and claimed that the share of Remainers in the UK was "larger and stronger" than that of Leavers. 

His recent remarks followed White House National Security Advisor John Bolton's interview with The Telegraph, in which he said that Brexit would provide the United Kingdom the opportunity to become a "strong and independent country" that would have a positive effect on the whole world and play a crucial role in NATO.

The developments unfold against the backdrop of UK Prime Minister Theresa May's announcement that she would be resigning as Conservative Party leader on 7 June following reports that backbenchers on the party's 1922 Committee would hold another no-confidence vote against her if she didn't set out a timetable for her departure.

The United Kingdom was supposed to leave the European Union on 29 March, but the prime minister opted to request a deadline extension until 31 October since she had repeatedly failed to gain support in Parliament and within her own party for the withdrawal deal she had negotiated with Brussels. The Irish backstop being one of the main bones of contention.