A Tory minister has condemned Kent County Council's huge £420,000 payout to its former managing director Katherine Kerswell - describing it as unacceptable and disturbing.

Local government minister Grant Shapps intervened in the row following the disclosure of the payout given to Mrs Kerswell, who unexpectedly left her job after less than two years.

Her total earnings for 2011-12 were £589,165 - thought to be one of the largest ever remuneration packages in local government.

Mrs Kerswell left KCC in December in controversial circumstances. The county council's Conservative administration insisted at the time her departure was connected to a re-organisation that involved scrapping her job to save money.

However, there was speculation relations with the Conservative-led authority had deteriorated.

Mr Shapps indicated his dismay over what he described as an eye-watering settlement, saying: "Whilst this bumper pay-off is deeply concerning I am extremely pleased that our new transparency rules have forced disclosure of it out into the open.

"These payouts would have been hushed up under Labour and hidden from the public. Ultimately the council must justify its actions but I find dipping into the public purse to make such an eye-watering pay off unacceptable."

His criticism has been echoed by unions representing KCC staff.

David Lloyd, secretary of the Kent branch of Unison, said: "When the previous chief executive (Peter Gilroy) left, why didn't they do a feasibility study then of whether another CEO was needed? It's bad planning by the politicians."

He added: "Feelings are running high locally. The anger I'm picking up is with the council, not Katherine Kerswell. So many people here have lost their jobs. It's frontline staff and low-paid women workers who have taken a hit, and it doesn't seem fair."

KCC leader Cllr Paul Carter (Con) said the council had been bound by restrictive employment laws which tied the authority's hands.

He said KCC was now spending £40m less on pay for staff and re-structuring of senior directors had saved £1m alone.