A major US real estate appraisal company was accused on Thursday of conspiring with one of the country’s biggest banks to inflate home prices in a scheme that New York state officials said helped fuel the mortgage crisis.

Andrew Cuomo, New York attorney-general, filed a lawsuit against First American saying its eAppraiseIT subsidiary gave in to pressure from Washington Mutual, the biggest savings and loans group in the US, to use a preferred list of appraisers who allegedly provided inflated values for homes.