A Labour MP is calling for government to do more to "criminalise buying sex".
Dame Diana Johnson - who leads a group on tackling sexual exploitation - said men in the UK who paid for sex were "fuelling a brutal sex-trafficking trade that is destroying lives".
She said "pimping websites" targeting vulnerable women should be banned, and more victim support should be provided.
The Home Office said its priority was to protect victims from harm and target those who exploit vulnerable people.
Dame Diana's call comes as politicians from the UK and Romania hold an online summit to decide on action to tackle human trafficking between the two countries.
In England and Wales, the acts of buying and selling sex are not illegal. However, many activities associated with prostitution are offences, such as links to exploitation.
Dame Diana, who is the MP for Hull North, told BBC Radio 4's Today programme: "One of the obvious things to do is criminalise paying for sex while we decriminalise the victims and give them support."
A specific area the All-Party Parliamentary Group on Commercial Sexual Exploitation wants action on is websites that traffickers use to target women to bring to the UK.
"They take the 'lover boy' approach where men befriend and become boyfriends of women and coerce them into trafficking," said Dame Diana.
"[They allow] men to access women in the areas that they live in and serious organised crime groups that are running this trade can move women between hotel rooms and brothels all around the country."
'Trade in human misery'
The Labour MP said Home Secretary Priti Patel could "bring forward legislation to criminalise the use of those websites and to close them down" straight away.
And she suggested looking at measures taken in Northern Ireland to offer more support to the victims caught up in this "trade in human misery and this abuse of women, who are being raped and sexually assaulted".
A Home Office spokeswoman said the government was "committed to tackling the abhorrent crimes of human trafficking and modern slavery and giving victims the support they need to rebuild their lives".
She added: "It is our priority to protect victims from harm and exploitation, and target those who exploit vulnerable people involved in prostitution."