The countries which spend the highest proportion of public money on pensions are Italy (32%), Greece (28%) and Portugal (26.4%).
The figures, from the Organisation for Economic Cooperation & Development, show that the average proportion in OECD countries is 18%.
The proportion is so high in southern countries partly as a result of the economic meltdown they have endured since the financial crisis during which other state spending was slashed, according to the OECD.
But high spending on pensions was not limited to the poorer southern European nations. Austria, Poland, France, Japan, Germany and Spain were all well above the 18% average.
The UK, on the other hand, was found to spend less than 12% of its total government budget on state pensions.
Iceland spent the lowest proportion of its government funds on pensions, at 4.5%.
The data is from 2011 but was published only this month in a report which said that despite having substantially different pension systems, countries were having to reform their pensions because of the impact of the financial crisis and the need to reduce government debt.
