More foreign travel restrictions should be imposed on known British sex offenders and more suspects prosecuted in the UK for crimes committed overseas, the government has been told.

In a 73-page report on protecting children in other countries from exploitation, the independent inquiry into child sexual abuse (IICSA) has called for legislation formalising use of international child protection certificates for those working and volunteering abroad.

The review, chaired by Prof Alexis Jay, is one of the multiple strands of IICSA’s investigation into child sexual abuse. It found that 361 UK nationals requested consular assistance abroad between 2013 and 2017 after being arrested for child sex offences. That figure, the study suggests, is likely to represent only a fraction of the overall number of British offenders.

In a public hearing last February, the inquiry was given evidence of abuse by British travellers in Kenya, Uganda, Malaysia, India, the Philippines, Cambodia, Indonesia, Thailand and Myanmar. Children are particularly vulnerable in states with high levels of poverty and corruption.

The global child sexual exploitation industry is estimated to be worth about £27.7bn, the report says, and as many as 2 million children are affected by it in south-east Asia. In the Philippines alone, at least 100,000 children may be exploited in the sex “industry”.

Abusers often target disadvantaged families where family members are willing to act as facilitators, the inquiry warns. In such cases, the disparity between the financial position of the abuser, and that of the victim and their family is a key factor.

The National Crime Agency (NCA) estimates that about 80,000 people in the UK present some kind of sexual threat online to children both in Britain and abroad. ​

High‐profile cases such as that of Paul Gadd, better known as the singer Gary Glitter, have raised awareness of the problem. In 2002, he was expelled from Cambodia over unspecified allegations and in 2006 convicted of sexually abusing two girls, aged 10 and 11, in Vietnam. On his return to the UK, he was placed on the sex offender register for life. He was subsequently tried for further offences against young girls and sentenced to 16 years’ imprisonment.

The report highlights gaps in the UK’s legal system that enable known offenders to abuse children abroad. “The number of orders restricting the foreign travel of sex offenders made under the Sexual Offences Act 2003 appears low every year,” it says. “Of the 5,550 sexual harm prevention orders imposed in England and Wales in 2017-18, foreign travel restrictions were imposed in just 11 cases … There is ample scope for greater use of foreign travel restriction orders.”

Section 72 of the Sexual Offences Act 2003, which allows individuals to be prosecuted in the UK for offences overseas, is also relatively rarely used, the report says. Only seven prosecutions were carried out under section 72 in England and Wales between 1997 and 2018 – a rate of one prosecution every three years.

Policy guidance that such prosecutions should only be pursued in the UK as a last resort is misleading, the report says. “Section 72 prosecutions should be initiated in appropriate cases, particularly where the quality of local justice [overseas] may be suspect.”

The report finds that the disclosure and barring system, including the international child protection certificate which overseas institutions can request when recruiting British nationals, is “confusing, inconsistent and in need of reform”.

Disaster areas can also pose a particular risk of sexual abuse for children. Oxfam staff were accused of sexually exploiting children in Haiti following an earthquake in 2010.

Some abusers operate in sophisticated networks that share tips and strategies to avoid detection. Richard Huckle, frequently described as “Britain’s worst paedophile” after being convicted of 71 counts of serious sexual assault while working in Malaysia, developed a clandestine group to further his activities.

Jay said: “The sexual abuse of children overseas by UK nationals is an urgent problem we cannot hide from. Current gaps in our legal system are allowing known offenders to travel abroad to target vulnerable children in less developed countries, and this is simply not acceptable.

“[We] hope this report and its recommendations will lead the authorities to tighten their grip on abusers who seek to exploit some of the most vulnerable children in the world.”

Kim Harrison, a solicitor at the law firm Slater and Gordon who has represented victims of child abuse abroad, said: “These findings are a damning indictment on the system’s attitude to child abuse. To punish paedophiles in this country but then allow them to travel abroad with unrestricted access to some of the world’s most vulnerable children is completely unacceptable.

“We have a moral duty to safeguard vulnerable youngsters from abuse anywhere, not just in the UK, and what is happening now is a dereliction of that duty which must be addressed as a matter of urgency.”

Responding to the report, a Home Office spokesperson said: “There can be no safe space for paedophiles to operate either here or abroad and we will do all we can to keep children safe. We continue to work closely with law enforcement in the UK and international partners to stop sex offenders from travelling abroad to prey on children, close down online networks and bring offenders to justice. Clearly there is more to be done.”