Right-of-centre think-tank Policy Exchange blamed the gap on national pay bargaining and called for public sector employers to be allowed to negotiate salary levels in line with local labour market conditions.
The analysis found that the average public sector worker enjoyed a 6.1% pay "premium" - £1400 a year - over someone in the private sector, taking into account age, gender, region, qualifications, length of employment and whether they were working full or part-time.
The report did not attempt to compare workers doing the same job in the public and private sectors.
In the North-East - excluding Tyne and Wear - the premium was 14.4% (£3200), in Merseyside 14.1%, in the South-West 13.6% and in Strathclyde 12.4%, according to Policy Exchange.
But in central London, the East and South East, the average public sector worker was paid less than in the private sector.
The think-tank said that reducing the pay and pensions of public sector workers to bring them in line with private sector norms would save £6.3 billion a year.
Unions said the report's figures were misleading, as most of the lowest paid public service jobs - such as cleaners, hospital porters, care assistants and school cooks - had been outsourced to the private sector, leaving higher paid employees like judges, doctors and senior civil servants on the public pay bill.
"When you start with false assumptions, your results are equally flawed," said Dave Prentis, the general secretary of public sector union Unison. "The idea that there is a public sector pay premium is a myth and dressing it up with dodgy statistics still won't make it true."
The new report draws on data produced by the independent Labour Force Survey for the first quarter of 2013.