By Ben Davies
BBC News political reporter
Young African girls are being brought into Britain and "deliberately impregnated" so they become eligible for council flats, MPs have been told.
The trafficking evidence was given to MPs at a Westminster committee hearing
Debbie Aruyo of Africans Unite Against Child Abuse (Afruca) said later some of the children were aged 12 to 16.
The victims were often sent alone into the UK, and placed in council care before falling prey to abuse, she said.
She suggested some of the girls ended up in prostitution while the flats were rented out in a "money making scam".
The Home Office said the government was "committed to tackling the appalling modern slave trade of human trafficking".
A spokesman stressed it was looking at responses to a recent public consultation about building up "existing tough" measures.
Ms Aruyo was one of several witnesses giving evidence to the Commons home affairs select committee's probe into immigration control, specifically about the issue of private fostering.
In written evidence submitted before the hearing, her organisation reported: "We have reports of cases involving Ugandan girls who have been trafficked purposely for council housing.
"They are brought in unaccompanied so they can go into local authority care, they are then impregnated to enable them to become eligible for council flats. The men then disappear and return once the housing problem is solved.
"It is believed by concerned members of the community that a sizeable proportion of the teenage pregnancy cases in London are as a result of this specific development in child trafficking."
Ms Aruyo and other witnesses were also asked about the issue of private fostering, where young Africans are taken from their parents and brought in on other children's passports.
She said there was a cultural acceptance in some African nations - particularly west Africa - that children could be looked after by relatives or even acquaintances of parents.
"It is not actually seen as wrong to give your child to an extended member of the family to look after in the hope or belief the child will be well looked after, go to school and so on and so forth," she told the cross-party committee.
"The problem we are finding is that a huge proportion of the children who are being privately fostered are being brought in by unscrupulous individuals who are actually bent on using them for exploitative purposes.
"A parent back home wouldn't bat an eyelid if somebody from here came to them and said 'I live in London I can look after your child for you'."
She said that if there was an ulterior motive the parent would not know it.
Those ulterior motives might include domestic servitude or claiming benefits or sexual exploitation.
Challenge the culture
New regulations introduced in July 2004 require people who are engaged in private fostering to notify local authorities if they are keeping the child for longer than 28 days.
The MPs also heard from Oyewu Ekelemu, a specialist African worker for Southwark Social Services, who said in her London borough there were not major concerns over the numbers involved in private fostering.
But she argued adults involved were often unaware that they were supposed to notify the authorities.
Even if they were aware sometimes private foster families had reasons not to admit their involvement.
She added that the culture of parents allowing other adults to foster their children should be challenged.
The Home Office stressed that work was under way on a number of fronts with collaboration between a number of agencies including the immigration service, police, social workers and local authorities.
"For example, the successful Operation Paladin Child, an operation undertaken by the Metropolitan Police Service to track unaccompanied children arriving at Heathrow, has led to the rollout of the 'Paladin model'," the spokesman said.
"This includes the creation of a permanent multi-agency partnership team based at Heathrow, to address the specific safeguarding needs of unaccompanied minors."