The death of a 21-year-old intern working at the London office of Bank of America Merrill Lynch is focusing attention on working conditions for interns in the U.K.

Moritz Erhardt, 21, a German-born intern who was studying business at the University of Michigan, was found dead on the floor of his apartment after working three days straight without sleep, colleagues say.

The bank has called Erhardt a "highly diligent intern at our company with a promising future" but refused to confirm how long he had worked before his death. It said it tries to offer interns "a positive experience" and uses internships as a way of getting to know graduates who are prospective employees.

But U.K. chat rooms were filling up with stories about the culture of long hours and brutal workloads in London’s financial district, including quotes from friends who said Erhardt "worked himself to death." He was in the midst of a 10-week internship.

Since the financial crisis, there are fewer jobs available and the most ambitious students are willing to accept long hours in return for the chance at a well-paid job, human resource experts say.

The coroner's office in East London said the cause of Erhardt's death would be released in four to five weeks, but police said it is not being treated as suspicious.

Erhardt was paid for his work and provided with housing, but across the Atlantic, the issue is not merely workload, but the fact that many U.S. interns are not paid.

White House interns campaign to be paid

The latest group to raise complaints over working long hours for free is White House interns, who have launched an online petition calling on President Barack Obama to pay interns.

The Fair Pay Campaign is appealing directly to the president, who this summer has been leaning on state governments to raise minimum wages.

"We have a minimum wage law in this country, and just because you call someone an intern doesn't mean you get out of it," said Mikey Franklin, the leader of the Fair Pay campaign.

An internship at the White House exposes students to influential people and should open doors for a career. But Franklin says only the privileged few can afford to take them on, because students from middle- and lower-income families are struggling with student loans and feeding and housing themselves.

Dozens of U.S. lawsuits

Unpaid internships have been an issue all summer in the U.S., with hundreds of interns filing lawsuits or launching complaints over working for free.

In June, a federal court ruled that Fox Searchlight Pictures violated wage laws by not paying interns who worked on the production of the 2010 movie Black Swan.

Under terms overseen by a New York judge, PBS talk show host Charlie Rose and his production company paid $110,000 US to settle a lawsuit brought by 189 former unpaid interns.

The Lean In organization was caught in a storm of controversy last week for advertising an unpaid internship position, with dozens of comments posted on its website and an online petition against unpaid positions.

There are dozens of lawsuits yet to be resolved, including ones against Elite Model Management, Hearst Magazine, Atlantic Records, the website Gawker and Warner Music Group.