More than 600 million people worldwide work excessively long hours, with Peruvians topping the list and Britons the worst offenders amongst rich nations, the International Labour Organisation reported on Thursday.

In a report on working trends in 50 countries, the United Nations agency said progress towards a maximum 48-hour week was still uneven nearly 100 years after the standard was agreed by ILO members.

More than half (50.9 percent) of Peruvians work more than 48 hours a week followed by South Koreans (49.5), Thais (46.7) and Pakistanis (44.4).

In developed countries, where working hours are generally shorter, 25.7 percent of British workers put in more than 48 hours a week followed by Israelis (25.5), Australians (20.4), Swiss (19.2) and U.S. workers (18.1).

"The good news is that progress has been made in regulating normal working hours in developing and transition countries, but overall the findings of this study are definitely worrying," said Jon C. Messenger, co-author of the ILO study.

The ILO says shorter working hours benefit workers' health and family lives, reduce accidents at the workplace and generally make workers more productive.

The growth of service industries, such as tourism and transport, and the expanding informal economy, where workers are not under contract, contributed to longer working hours, the ILO said.

Both elements are signs of increasing globalization, it said.