Britain could face massive political and social unrest on a scale similar to Greece if the next government cannot rally the public behind plans to cut the £178bn deficit, Liberal Democrat leader Nick Clegg will warn today.

In a speech to the Institute for Public Policy Research, Mr Clegg will say a new government could be “torn to pieces” if it tries to “ram through” spending cuts without wider public consent.

If we do not find a way to take the people of Britain with us on this difficult journey of deficit reduction, we will not be able to make the journey

He will argue that the scale of the cuts needed to tackle the deficit is so great, it will be essential to engage the public in the process.

If the structural deficit in the public finances is to be eliminated without further tax increases, at some point in the next eight years government spending will have to fall by as much as 10 per cent, he will say.

“That means there is an enormous risk ahead. In a democracy, dramatic change cannot be imposed from above or it will fail. It has to be led by a process of political engagement,” he will say.

“You only have to look at the scale of industrial unrest in Greece to see that it is impossible to reduce a public deficit quickly if you do not find a way to persuade people to go along with the process.

“If we do not find a way to take the people of Britain with us on this difficult journey of deficit reduction, we will not be able to make the journey. We will instead follow Greece down the road to economic, political and social disruption.”