Tony Blair has echoed Donald Trump in calling for ISIS to be 'crushed', warning that failure to take the fight directly to the Islamic terrorist group will result in 'many more victims' in Western cities.

The former prime minister urged David Cameron to 'assume leadership' in the fight against ISIS and said Britain and the US must step up their military support of local groups fighting ISIS in Syria, Iraq and Libya.

Warning that the West would face 'increasingly frequent acts of terrorism' like the deadly attacks witnessed in Brussels and Paris, Mr Blair said: 'ISIS has to be eliminated with greater speed and vigour'.

Tony Blair, pictured right, has echoed Republican Donald Trump, pictured left, in calling for ISIS to be 'crushed'

'Unfortunately the attacks are going to keep coming,' he wrote in an article for the Sunday Times.

He wants an international rapid reaction force to be created to kill off future terrorist groups before they can grow to the extent ISIS has.

In a strongly worded warning that will attract claims of scaremongering, Mr Blair predicted terrorists will commit 'an act of such size and horror that we will change our posture' but said by then it would be too late to defeat terrorism without measures that 'contradict our basic value system'.

Mr Blair also struck a similar tone to Mr Trump in saying the West needs to 'end the denial about what is happening and has happened over a significant period of time within Islam'.

Mr Blair wrote: 'We can use local allies in the fight, but they need equipment and where they need active, on-the-ground, military support from us, we should give it.

'The Americans are doing this now — at least to a degree and with effect. But to have allowed Isis to become the largest militia in Libya right on Europe's doorstep is extraordinary. It has to be crushed.'

Mr Trump, who is favourite to win the Republican party's nomination for November's US Presidential election, said he would 'hit ISIS so hard you wouldn't believe it' if he becomes US President later this year.

We can use local allies in the fight, but they need equipment and where they need active, on-the-ground, military support from us, we should give it Tony Blair

In an interview with DailyMail.com U.S. Editor-at-Large Piers Morgan on ITV's Good Morning Britain, Mr Trump said: 'I'd get the people over there to put up their soldiers because it's about time somebody did it.

'But I'd have such backup like you've never seen before in terms of air power, airstrikes etc, and you've got to take them out - and you've got to take them out harshly, and you've got to take them out fast.'

Later he refused to rule out using nuclear weapons to defeat ISIS, saying: 'We need unpredictability' to defeat the terror group.

Mr Blair, warning of further attacks if Britain fails to step up its fight against ISIS, wrote: 'The attacks in Belgium were shocking. Unfortunately the attacks are going to keep coming.

'If you have no compunction about killing wholly innocent civilians and are prepared to die in the act of doing so, societies like ours offer vast possibilities of vulnerability.'

'Otherwise, we will have periodic but increasingly frequent acts of terrorism that will result in many more victims and start to destabilise our political and social cohesion.

'Eventually the terrorists will commit an act of such size and horror that we will change our posture; but by then the battle will be much harder to win without measures that contradict our basic value system.'

Warning: Mr Blair said the West would face 'increasingly frequent acts of terrorism' like the Brussels attacks

The former Labour prime minister is awaiting the publication of the seven-year Chilcot inquiry into the Iraq war, which many on the left of British politics blame for sowing the seeds of Islamic extremism.

But in a coded attack on one of those – Labour leader Jeremy Corbyn – Mr Blair wrote today: 'We must escape from the paralysing grip of the present political discourse stuck between a right wing that is now tipping into bigotry against Muslims as a whole and a left that thinks that calling it 'Islamism' is stigmatic and prefers to believe that in any event we have caused all of this through western policy although the countries now affected cover the gamut of policy positions from the most interventionist to the expressly pacific.

'This discourse disables the alliance we need within Islam.'

Mr Blair founded the Tony Blair Faith Foundation which provides practical support to counter religious conflict and extremism. He previously served as peace envoy to the Middle East and works in eight African countries advising presidents.

He was prime minister during the 2003 invasion of Iraq and is expected to come in for criticism in the official inquiry report into the Iraq war - the Chilcot report - when it is finally published.

In the article he called for Western ground forces to take action wherever a terrorist group emerges as they were necessary to win the fight against extremism.