Kent County Council has defended the salaries it pays to its chief executive and senior officers in the face of further criticism of their earnings.

A survey by the Taxpayers’ Alliance showed the number of Kent County Council staff earning more than £100,000 has nearly doubled in a year to 30 and that the authority’s chief executive Peter Gilroy enjoyed a salary of £255,000 in 2007-2008, making him the third highest paid council chief in the country.

Council leader Cllr Paul Carter (Con) said KCC was a large authority and had to pay what was the "market rate" to attract the best staff.

He said: "Kent County Council has to compete in a marketplace to attract the very best staff. Kent is the largest local authority in the country with an annual spend of £2.2bn a year, educating 220,000 children, maintaining 5,000 miles of roads and 4,000 miles of pavements, fixing 5,000 street lights a month, getting rid of 800,000 tons of rubbish every year and providing services for many of our 238,600 over 65 population - and these are just a few examples. Markets move up and down and we will move with the times to recruit the best possible staff to Kent County Council."

Labour opposition group leader Cllr Mike Eddy said: "It would be so much better for senior staff pay, including the chief executive, to be agreed by an independent review body. The question that has to be addressed it what exactly is the market rate at a time of a recession," he said.

Meanwhile, shadow chancellor George Osborne (Con) said it was "difficult to justify" very high salaries in the public sector and any quango boss being paid more than the prime minister would have to justify themselves to the Treasury.

"It sends a very powerful signal throughout the public sector that the age of excess is over and we need an age of restraint and responsibility."

The recently-retired children’s services director Graham Badman was the second best-paid officer at County Hall on a salary of £195,000, followed by Oliver Mills, the managing director of adult social services, who received £175,000.

Amanda Honey, KCC’s communities director, received £155,000 while Lynda McMullan, the director finance, received £135,000. Of the 30, seventeen were paid £105,000.