Britain should be part of the proposed EU army and stay in the union despite the efforts of "backwards-looking" Euroskeptics to withdraw, controversial former PM Tony Blair claims.

Writing in Newsweek magazine, Blair said there has never been a stronger need for European unity, on defense and elsewhere, and that the EU must bind together and ignore those who are "forever looking backward to break the union asunder."

Blair said the rise of China and India as major global powers meant the balance of global power may shift. If Britain wished to stay relevant, he argued, it must remain bound to Europe.

He said smaller countries which have population of below 100 million would be wise to rely on their "geographical relationships" to stay ahead of the game and a major part if this involves a pan-European defense force.

"I would argue that in the medium term, there will be a growing requirement for Europe to build defense capability.