Blair: Mali war like fight against communism

He also attempted to compare the West's fight against al-Qaida to that against "revolutionary communism."

Speaking on the BBC's Andrew Marr show the former PM said that David Cameron faced difficult decisions but warned the cost of standing aside would be far greater.

"I think we should acknowledge how difficult these decisions are," he said.

"Sometimes in politics you come across a decision which the choice is very binary, you go this way or that way and whichever way you go the choice is very messy."

He added: "We always want in the West, quite naturally, to go in and go out, and think there is a clean result. It's not going to happen like that. We now know that. It is going to be long and difficult and messy.

"My point is very simple though: if you don't intervene and let it happen, it is also going to be long, difficult and messy and possibly a lot worse. It's a very difficult decision.

"We are certainly talking about a generation. I think a better way to look at it is like the fight the West had over a long period of time with revolutionary communism."

Ministers have insisted they are aware of the risk of mission creep in Mali and insisted there were no plans to put British boots on the ground in the West African state.

Foreign Secretary William Hague today said that remained the government's intention but ducked calls to guarantee that troops would not be sucked into the conflict at a later date.