The top five banks accounted for over half of the total number of consumer complaints handled by the Financial Ombudsman Service over the past year.

The Financial Ombudsman Service (FOS) has made available for the first time a range of complaints data relating to individually named financial businesses – including banks, insurance companies and investment firms.

The data includes the number of complaints received about individual businesses and the percentage of complaints upheld by the ombudsman service in favour of consumers.

The data published on the ombudsman’s website covers consumer complaints handled by the ombudsman service between 1 January and 30 June 2009. During this six-month period, the ombudsman service received a total of 69,841 new complaints – of which 87% related to 142 financial businesses (out of more than 100,000 businesses covered by the ombudsman).

Barclays topped the list with 8,283 complaints, and Bank of Scotland had the most mortgage and home finance-related complaints (563).

The number of new complaints about each of these individual businesses ranged from 31 to 8,283. Five banking groups each had more than 3,000 complaints which together accounted for 38,286 cases – over half of all the new complaints received by the ombudsman during this six-month period.

The number of new complaints against each business is likely to be affected by the business size. However, FOS says that experts consulted by the ombudsman have been unable so far to agree how size (or market share) should be taken into account, when comparing complaints statistics across the financial services sector.

The data published shows that the ombudsman service upheld an average of 59% of complaints in favour of consumers. Across the 142 individual businesses included in the complaints data, this uphold rate varied substantially between 11% and 95%.

The ombudsman service upheld 61% of banking-related complaints, 41% of mortgage complaints, 70% of general-insurance complaints and 42% of investment-related complaints.

Chairman, Sir Christopher Kelly, said: The board of the Financial Ombudsman Service welcomes the publication of this detailed information, as part of our work to help financial businesses improve their complaints handling – and to reduce the number of unresolved disputes that have to be referred to the ombudsman service.

“I will now be writing to the chairmen of the financial businesses that generate the largest proportion of our complaints workload