The letter, sent to The Guardian newspaper, warned that poverty and increasing inequality was causing a new wave of distress in Britain.

It said that what they described as the Government’s “get to work therapy” was “manifestly not therapy at all”.

“The profoundly disturbing psychological and quality-of-life implications of the Coalition Government’s cuts and policies have yet to be mentioned in the election campaign,” the letter said.

“Counsellors and psychotherapists in the public and private sectors find themselves at the coal face in responding to the effects of austerity politics on the emotional state of the nation.

“The past five years have seen a radical shift in the kinds of issues generating distress in our clients: increasing inequality and outright poverty, families forced to move against their wishes, and, perhaps most important, benefi ts claimants (including disabled and ill people) and those seeking work being subjected to a quite new, intimidatory kind of disciplinary regime.”

It added that society had been “thrown completely off balance by the emotional toxicity of neoliberal thinking” that has been affecting Britain in “profound ways, the distressing effects of which are often most visible in the therapist’s consulting room”.

“This letter sounds the starting-bell for a broad-based campaign of organisations and professionals against the damage that neoliberalism is doing to the nation’s mental health,” the letter said.

A Conservative spokesman said: “Under this government inequality has fallen, child poverty is down and there are now 1.9 million more people in jobs than there was at the last election.

“We have legislated to ensure mental health is treated equally to physically health and are introducing new waiting time standards.

“Overall spending on mental health has increased, including over £400m to make a choice of psychological therapies available for everyone who needs them.”