The Financial Services Authority (FSA) has published details of complaints from customers about banks and insurers that reveal a 59 per cent increase in the first six months of 2012.
Barclays topped the table of complaints against individual banks with 442,266.
However, Lloyds Banking Group had the most complaints against it, with 794,000, including two banks, Lloyds TSB and Bank of Scotland.
The FSA says that the increase is driven by a rise in complaints about the mis-selling of payment protection insurance (PPI), which were up by 129 per cent, reaching a total of 2.2 million in just six months.
In total, banks have set aside £9 billion so far for PPI compensation and less than half has been claimed so complaints are expected to remain at a high level for the next year or so.
PPI was designed to protect and cover loan repayments in the event of redundancy or illness but many people sold the product could not have claimed on the insurance or did not even realise they were being sold the loan. It is the biggest mis-selling scandal of the last decade.
The FSA report details the complaints made against banks, insurers, home finance, life assurance, pensions and the investments sector.
General complaints about banks rose by five per cent in the first six months of 2012, up to 828,040. Santander was the bank with the largest number of complaints about banking, 147,113.
Last month the Financial Ombudsman Service (FOS) said that it was receiving 1,500 new complaints every day about PPI.
The Financial Ombudsman Service revealed in August that it was receiving 1,500 new complaints daily about PPI. The FOS has criticised banks for not settling claims as quickly as they said they would.
However, the banks have said that the process of assessing and settling the claims is proving difficult because of the number of false claims being submitted by claims management companies.