The government has been urged to improve enforcement of the rules around sexual harassment in the workplace after research found there was weak oversight of vulnerable workers.

Focus on Labour Exploitation, or Flex, a campaign group, identified a gap in enforcement of sexual harassment rules in a report published this week on working conditions for cleaners in the UK. It found that 33 per cent of the mostly female workers surveyed had suffered behaviour ranging from sexualised comments about their appearance to sexual assault.

Although the cleaners could bring cases to employment tribunals, sexual harassment was outside the remit of the Health and Safety Executive, which regulates workplace safety. Meanwhile, the Equality and Human Rights Commission, the equalities watchdog, lacks the HSE’s enforcement powers.

“It is clear that the gap in state enforcement on this issue needs to be addressed,” the report said.

Matthew Taylor, director of labour market enforcement, who sets policy for the UK’s labour watchdogs, said the report’s findings were “really concerning”. “I think that what [the report has] exposed underlines the need to think about labour market compliance through an equalities lens,” Mr Taylor said.

Marisol Urbano, a cleaner and Flex peer researcher originally from Ecuador, said she had felt “desolate” in the two years since she started suffering verbal harassment and unwanted touching from a man she supervised.

“You just feel mistreated,” Ms Urbano said. “If there was a clear place to go, external to the company, where we could report the abuse . . . that would really help us report sexual harassment and would help us protect our wellbeing.”

Cleaners are particularly vulnerable and often lack workplace protection. Many work excessive hours at below the national minimum wage. A high proportion — 32 per cent across England and 53 per cent in London — are migrants, often originally from Latin America or eastern Europe, and many speak little or no English.

Flex’s research found that 61 per cent of the cleaners they surveyed reported problems over pay, mainly being paid for fewer hours than they had worked. Some 47 per cent also said they did not receive sick pay when they were ill; 86 per cent of those surveyed reported having suffered some kind of health issue as a result of their work.

Enforcement of workplace regulations is patchy. The UK’s labour inspection bodies — the Gangmasters’ and Labour Abuse Authority, HMRC Minimum Wage and the Employment Agency Standards Inspectorate — are understaffed and have only half the number of inspectors that the International Labour Organization recommends.

Meri Ahlberg, Flex’s research manager, said it seemed little had been done to address the sector’s shortcomings since an EHRC report on the cleaning industry in 2014.

The Health and Safety Executive insisted that, while sexual harassment was a serious issue, it was outside its workplace safety remit. “Risks to workers such as sexual harassment require close multi-agency co-ordination, and we remain committed to such collaboration, in this case with agencies such as the police or the Equality and Human Rights Commission,” it said.

The EHRC said it stood ready to “take employers to task” over inappropriate treatment, including by signing legally binding agreements on worker protection with companies whose employees have won employment tribunal cases over the issue.

“We have . . . published guidance which sets out legal requirements and provides practical examples of how to prevent and respond to harassment,” said the EHRC. “We hope that this will shift the burden back on to employers.”