The term "internship" currently has no legal status in the U.K when dealing with pay or working conditions, so firms are free to design their intern programs.

But CIPD, the U.K.'s largest human resources body, said its policy guidelines will likely be changed after this incident to include suggested working hours for interns.

"What it shows is that young people need a bit more support," Katerina Rudiger, head of skills and policy campaigns at CIPD, told CNBC. She added that young people were desperate to work hard, sometimes for free, in order to earn a job in this difficult economic climate.

(Read more: Brussels interns protest working conditions, lack of pay)



John McIvor, BoAML's head of international communications, said Tuesday he could not confirm the circumstances surrounding Erhardt's death or his working hours. The bank said it was deeply shocked and saddened by the death.

"The whole point about internships is to give students a positive experience and to get to know our firm, and us to know them well, so we can work out who would be the best fit to join the company full-time after they graduate," McIvor said.

A former employee at BoAML, who asked to remain anonymous, said interns tended to compete with each other in order to prove themselves to bosses in the hope of gaining a permanent job when graduating. Long hours were common at most banks, he said, especially the larger U.S. banks.

Other former interns agreed, saying the culture of long-working hours was widespread. They were thankful this current case might put the work environment at banks in more focus.

(Op-Ed: Don't force businesses to pay interns)



A former intern at another investment bank said he had worked a hundred hours a week as an intern at the bank, and that first year graduate analysts worked the same hours, before cutting back to about 80-90 hours per week in their second year.