The US government should help revive the moribund market for big mortgages by getting Fannie Mae and Freddie Mac to buy large home loans from banks, the chief executive of the lender Wells Fargo urged on Tuesday.

In an interview with the Financial Times, John Stumpf, whose bank originates a quarter of all US mortgages, called for an increase in the size of loans purchased by Fannie and Freddie, the troubled finance groups controlled by the authorities.