An investigation has been launched after claims that Home Office contractors paid for sex while deporting people abroad, the Guardian has learned. Five whistleblowers have said some colleagues regularly paid sex workers on overnight stopovers over a period of 10 years after accompanying migrants on flights from the UK. It is understood that the Home Office permanent secretary, Matthew Rycroft, has raised concerns about the allegations with the firm Mitie, which has held the contract to manage deportations since May 2018. Mitie said it was conducting a full investigation into the claims and had so far found no evidence that the behaviour had occurred since it took on the contract. The allegations have prompted charities to criticise the Home Office for allowing taxpayers’ “hard earned money” to be used for “predatory sex tourism”. The whistleblowers have passed the Guardian a dozen names of colleagues they say paid sex workers over the course of a decade. They claim this happened in cities including Nairobi in Kenya, Johannesburg in South Africa, Hanoi in Vietnam, Rio de Janeiro in Brazil and Bucharest in Romania. One Home Office contractor said they had been shocked at what they had seen while escorting people overseas. “On one job, two of us sat in the bar while three of the others in the team went off with [sex workers],” they said. “One had a phone which he called his ‘little black book’ specially for jobs abroad to arrange these liaisons.” Another contractor said: “The money paid by these Home Office contractors using sex workers while abroad doing deportations goes further than it would in the UK. But it is taxpayers’ money being used to fly us to these places where sex is being paid for,” they said. A third contractor told the Guardian: “This practice among Home Office contractors has gone on for as long as I can remember … A lot of hotels, especially in places like Nairobi, are full of prostitutes and they are cheap. It’s a thing some of the men do because it’s there, it’s available.” Stephen Kinnock, Labour’s immigration spokesperson, described the reports as deeply disturbing and called on the Home Office to investigate the allegations immediately. Bella Sankey, the director of Detention Action, said: “The deportation industry wastes millions of taxpayer pounds to rip loving families apart and leave thousands of British children growing up in poverty. It is rubbing salt in that wound to learn that the Home Office’s contractors may have been engaged in predatory sex tourism while abroad on our hard-earned money.” Steve Valdez-Symonds, Amnesty International UK’s refugee and migrant rights director, said the latest allegations drew attention to the need for the Home Office to critically reassess its use of private contractors to carry out immigration tasks. “Contracting out requires serious effort to ensure continued Home Office responsibility for these tasks is made real in practice; and it must never be treated as a means of avoiding accountability,” he said. A Mitie spokesperson said: “The group’s senior management recently became aware of allegations relating to anonymous and historic claims regarding inappropriate behaviour by a small number of employees working on the Overseas Escorting contract. We have not been provided with evidence to substantiate these claims, nor have any details of specific instances been shared with us. However, given the serious nature of these allegations, we have been conducting an investigation. “To date, we have found no evidence that this behaviour occurred during our time managing this contract, which commenced in May 2018. We have strict professional standards, underpinned by a rigorous code of conduct, which employees must adhere to at all times when on company business. Any employees found to fall short of these standards will be subject to disciplinary action.” A Home Office spokesperson said: “We take all reports of sexual exploitation extremely seriously and if these disturbing allegations are proven, we expect Mitie to take swift and robust action. We have instructed Mitie to provide us with a full account of their investigation. We expect the highest standards of behaviour from our suppliers, both in the UK and overseas, and if we find any wrongdoing has taken place, we will always act in the strongest possible terms.”