Flouting ethical standards leads to bad government decision-making and risks “disaster”, former Islington MP Chris Smith has warned.

Rounding on the conduct of Boris Johnson’s administration, Baron Smith of Finsbury - who used to be a councillor in Islington and a Labour Cabinet minister - argued the key principles of public life, which include integrity, honesty and openness, were being “regularly undermined”.

The non-affiliated peer, who is a former member of the Committee on Standards in Public Life, levelled his criticism during a debate in the House of Lords following a series of Government controversies linked to lobbying, and claims of bullying and cronyism.

Citing a catalogue of cases in which he argued standards of public life had been breached, Lord Smith said: “I fear that these principles, on which the integrity of our entire system of governance is founded, are being regularly undermined.

“No government have ever got this completely right, but I have never seen a government getting so much so wrong.

“Too many people in public life, including senior figures in Government, are disregarding the ethical standards that ought to govern behaviour and action."

Branding the situation as “serious”, the former Environment Agency chairman added: “Leadership to change this downward drift has to start from the top. The Prime Minister, above anyone else, has to set, lead and enforce the standards. I doubt he will, but that does not diminish the need.”

Labour former Cabinet minister Lord Blunkett, who opened the debate on standards in public life, said: “How can you rail against corruption and the misuse of power elsewhere if you are not incredibly careful that you always demonstrate that you understand the importance of avoiding that misuse in your own country?”

But responding, Cabinet Office minister Lord True said: “I differ with some on the idea that we have now descended into an age of rust and that standards now are uniquely poor or corrupt.

“I do not believe that is true and, as I said at the outset, it does a disservice to the vast bulk of those in this place and in public service.”