The gap between public and private sector pensions in Britain is the widest in the developed world, according to the first report to measure "pensions apartheid" among younger workers.

The Organisation for Economic Co-operation and Development found UK civil servants' pension promises were so generous that an average worker joining the workforce two years ago will receive a 6pc pay rise when they reach retirement.

The UK is the only country where civil servants will enjoy pensions worth more than 100pc of their final salary, it said. Such arrangements will also apply to many other UK public sector workers as their pensions are equivalent to or more generous than civil servants'.

By contrast a private sector worker can expect a pay cut of nearly 50pc with a total pension worth just over half (51.4pc) their final salary, assuming they retire at age 68.

At 54.6 percentage points it means the gap between civil servants and private sector workers is more than twice the average across all OECD countries, where the difference is 20 percentage points wide.