According to The Guardian, child abusers have been infiltrating aid agencies working in developing countries.

UK agencies say recent attempts to tighten up legislation regarding child abuse in the UK as well as growing awareness of the problem mean paedophiles are having to exploit the remaining loopholes open to them.

They say the problem in developing countries is often down to the scale of other problems they are facing, lack of awareness about how paedophiles operate and even a refusal to admit abuse exists.

According to research, child sex abusers work hard to establish themselves as trusted individuals with children, often spending months creating opportunities to offend.

They often select vulnerable children who appeared to lack self-confidence - precisely the kind of children which charities often deal with.

Police checks

In the past, UK charities have had problems checking up on potential staff as they have not had access to the same level of checks as statutory organisations.

They have had to rely on references and police checks, which have only been required since 1992.

However, Dr Michelle Elliott of Kidscape says thorough checks can be "very time-consuming" and may involve relying on tip-offs.

The Home Office says this will change when the Criminal Records Bureau comes in in the next two years or so.

It will establish a one-stop shop where, for a small fee, children's agencies can go to check police records as well as Department of Health and Department for Education and Employment records.

These include information about staff who have been suspended, cautioned or sacked because of concerns about abuse.

Children's agencies say hardened paedophiles tend to move jobs as soon as suspicion is cast on them, so avoiding being sacked.

This makes it easier for them to move to another area, perhaps change their name and find employment with children again.

Until now, social services have not been obliged to pass information on, but under new legislation coming in soon that will change and the information will be centrally stored.

It could also be shared with international bodies.

Other legislation, such as the 1997 Sex Offenders Act, make it easier for agencies to keep track of child abusers.

This allows for people accused of sex crimes overseas to be prosecuted in the UK.

International agencies, however, often work with local staff in countries which may not have a checking system.

However, Paul Nolan, child protection development manager at Save the Children Fund (SCF), said: "Although checks are important, they can encourage complacency.

"Very few offences are come to light and fewer are prosecuted.

"What is important is developing a culture where staff are aware of child abuse, how to prevent it happening and how to report it."

Closing loopholes

As part of its commitment to children's rights, SCF is working with governments abroad to raise awareness about abuse and how to prevent it.

But some countries prefer to sweep the issue under the carpet.

Orphans in developing countries may be targets for UK paedophiles

"There is a learning curve that has to be gone through to recognise the problem of child abuse. Our work has to be sensitive to the local context," said Mr Nolan.

The National Society for the Prevention of Cruelty against Children (NSPCC) says, despite improved awareness about child abuse in the UK, there is no room for complacency.

It wants to see independent visitors become a legal requirement for children's homes, boarding schools and other residential settings.

It believes this is crucial to ensure abuse is reported and acted on. The spokeswoman said children may not trust social services officials who may be seen as being too close to abusive staff.

The NSPCC also wants to see more awareness among parents and children about paedophiles so they can spot the signs before abuse occurs.

"They are not nasty old men who pounce on children. They tend to be very good at playing the system and come across as so credible and child-friendly," said the spokeswoman.