A Christian campaign group has called for caution as a government scheme rolls out allowing Britons to shelter Ukrainian refugees in their own homes.
CARE welcomed the intention behind the Homes for Ukraine scheme, launched as millions flee the war in Ukraine, but warned that there was "potential for abuse".
The warning was issued on Monday, the same day as a government website was to go live allowing people to express their interest in becoming a sponsor.
The government has offered people £350 a month to take a Ukrainian refugee into their home.
CARE's human trafficking lead, Lauren Agnew, said that proper vetting must be in place so that refugees do not fall victim to modern slavery.
"The Homes for Ukraine scheme is well-motivated and could benefit a great number of individuals but the logistics of it must be weighed carefully," she said.
"With large numbers of applications needing to be processed quickly, red flags could be missed in the vetting of potential hosts."
She called for "rigorous safeguarding measures" to ensure the safety and wellbeing of refugees for the duration of their stay in the UK.
These measures should include follow-up checks to ensure refugees are not exploited by their hosts, Agnew said.
"Recent statistics from the National Crime Agency estimate there are at least 6,000-8,000 modern slavery offenders in the UK," she continued.
"We can be certain that some of this number will be seeing the Homes for Ukraine scheme as an opportunity to turn a profit at the expense of vulnerable individuals seeking refuge in the UK.
"Setting refugees up in homes around the UK is not the end of the story. There must be follow-up checks to ensure these individuals are not being exploited.
"We must remember that refugees are extremely vulnerable. They must not be allowed to fall off the radar."
The Refugee Council has raised similar concerns about the safety and wellbeing of the refugees but also the level of support available for their sponsors.
"We are talking about very traumatised women and children whose experiences are unique, and the level of support needs to match that," it said.
"It's like asking people to be foster carers without any robust checks, training or having a social worker in place to support them.
"Those coming here who have already had their lives turned upside down, will also not have full rights to benefits, so there is a real risk they could end up homeless if they have to leave the sponsors or extended family home which would be completely devastating.
"It's vital they can quickly access GPs, mental health services and schools to ensure they have the support they will so desperately need to rebuild their lives in the UK."
