"(It) creates a sense of fear inside the civil service at senior level which will prevent them for giving the honest advice to ministers that they need to hear," he told Reuters.
Mark Serwotka, general secretary of the Public and Commercial Services Union, the largest trade union representing British civil servants, agreed.
"I think the whole attitude towards civil servants from the political side is worsening," said one former civil servant on condition of anonymity.
Former civil servants such as Kerslake fear for its future.
"I call it the 'how high' phase, which is ministers saying jump and civil servants say how high," Kerslake said.