Britain will have to keep fighting wars abroad for a generation if global terrorism is to be defeated, Tony Blair said today.

Although he admitted that decisions to intervene in military conflicts during his premiership had been controversial, the Prime Minister said that "conflict and therefore casualty" would have to continue long after he leaves Downing Street later this year and promised increased spending for the Armed Forces to maintain Britain's position as a world power.

Speaking to the Royal Navy, Mr Blair was unapologetic about his decision to go into Iraq and Afghanistan, saying that military action played a key part in defeating the terrorist enemy. If Britain shrank its role to peacekeeping alone, its "reach, effect and influence (would be) qualitatively reduced", he said, adding that retreat from the enemy would be a "catastrophe".

But his words were derided by critics, with one left-wing Labour MP saying they were the "delusional ramblings of a Prime Minister who has… made the most catastrophic foreign policy mistakes since Suez".

Acknowledging that there was anger and scepticism within the military, Mr Blair admitted that personnel were working harder and for longer missions than planned, and that there were "real problems" with accommodation. He insisted though that defence spending had been "roughly constant" since 1997 and was still one of the highest in the world.

Speaking on board HMS Albion in Plymouth, Mr Blair said that the covenant between the forces and the public had to be renewed, and as soldiers were asked to undertake unprecedented challenges, the public had to recognise the importance of Britain’s military campaigns to international security.

"They need to be prepared for the long as well as the short campaign, to see our participation alongside allies in such conflict not as an atavistic, misguided attempt to recapture past glories, but as a necessary engagement in order for us to protect our security and advance our interests and values in the modern world."

"What we face is not a criminal conspiracy or even a fanatical but fringe terrorist organisation," he said, adding that the enemy was not a conventional one that could be defeated through conventional means.

"It has realised two things: the power of terrorism to cause chaos, hinder and displace political progress, especially through suicide missions; and the reluctance of western opinion to countenance long campaigns, especially when the account it receives is via a modern media driven by the impact of pictures."

Retreating from battle he said, would only strengthen terrorism, enabling it to spread and increase its number. "Given the nature of it and how its roots developed, long before any of the recent controversies of foreign policy, such retreat would be futile."

Mr Blair admitted that soldiers’ feelings were more raw than ever and that the public was "unnerved" by the lack of a clear victory. "For their part, the military and especially their families will feel they are being asked to take on a task of a different magnitude and nature," he said.

"Any grievances, any issues to do with military life, will be more raw, more sensitive, more prone to cause resentment. Public opinion will be divided, feel that the cost is too great, the campaign too long, and be unnerved by the absence of ‘victory’ in the normal way they would reckon it."

Mr Blair blamed the media for what he said was its role in encouraging a negative public attitude towards his policy of intervention. "They [the public] will be constantly bombarded by the propaganda of the enemy, often quite sympathetically treated by their own media, to the effect that it’s really all ‘our’ — that is the West’s — fault," he said.

The Prime Minister argued that if Britain gave up its war-fighting capability, it would suffer a reduction of its so-called "soft" power, in diplomacy and on such global issues as climate change and poverty in Africa.

"The world is interdependent," he said. "That means we work in alliance with others. But it also means problems interconnect. Poverty in Africa can’t be solved simply by the presence of aid.

"It needs the absence of conflict. Failed states threaten us as well as their own people. Terrorism destroys progress. Terrorism can’t be defeated by military means alone. But it can’t be defeated without it."

William Hague, Shadow Foreign Secretary, said Mr Blair’s speech had come too late to be meaningful, describing it as "yet another episode of ‘Ten Wasted Years’, by Tony Blair."

"After a decade in power, his legacy will be an overstretched Army, Navy and Air Force," he said. "Soldiers serving on operations want to know what Mr Blair is going to do now about the poor accommodation they and their families have to live in, the withdrawal of allowances that they used to receive whilst on operations and the medical care given to our troops on their return home.

And Sir Menzies Campbell, Liberal Democrat leader, said: "The Prime Minister does not seem to have learnt the lessons of Iraq. Without United Nations authority the military action was illegal and severely damaged Britain’s reputation. This will be the Prime Minister’s legacy.

"The relationship with America is of vital importance to the UK but it has to be reviewed, renewed and restored. We need a partnership of influence not subordination. Britain has to learn that we will only be at our most effective in tackling terrorism when we operate within the rules and with allies of the same mind."

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