Banks were urged today to improve the way they treat bereaved customers.
Chairman of the Commons' Treasury Select Committee, John McFall MP said relatives often faced "inadequate and chaotic" procedures when they tried to access their loved ones' funds.
He wants the City watchdog to create a code of conduct for banks and other financial institutions governing how they administer estates.
Mr McFall told the BBC: "The main issues are treating people fairly at the most stressful time of their lives. We have had evidence that people have had to jump through unnecessary hurdles as a result of their business with banks and financial institutions.
"I am writing to the Financial Services Authority so that they can remind these institutions that treating customers fairly is a primary responsibility.
"They can develop a code of conduct so that it makes things easier for people at the most stressful time of their lives, rather than harder."
One widow told how after more than a year of writing letters and making phone calls to access her late husband's £20,000 in Isas, she had still not received the money.
Bereavement support group the Way Foundation said it feared there were cases where financial institutions unnecessarily delayed payment to bereaved relatives.
The foundation's chairman, Caroline Doughty, said the problems were avoidable.
"We would never expect people to walk into a bank, wave a piece of paper and say, 'Oh my husband is dead, can I have all his money?'
"But I think what needs to happen is more training across the board so that people working for any type of institution know how to have this difficult conversation with a client who has rung up."
The British Bankers' Association cited potential delays due to legal technicalities, especially if an account was not held in joint names.
But the organisation said bank staff training included guidance on helping customers who had recently been bereaved.