The top 25 US originators of subprime mortgages – the toxic assets that sparked the global financial crisis – spent almost $370m in Washington over the past decade on lobbying and campaign donations as they tried to ward off tighter regulation of their industry, an investigation has shown.

The study, which will be released today by the Center for Public Integrity, a non-profit investigative journalism organisation, is likely to strengthen public calls for much tougher financial regulation in the US.

It shows that most of the top 25 originators, most of which are now bankrupt, were either owned or heavily financed by the nation's largest banks, including Citigroup, Goldman Sachs, Wells Fargo, JPMorgan and Bank of America. Together, they originated $1,000bn in subprime mortgages in 2005-07 – almost three-quarters of the total.