Some criminals specifically target international students, telephoning them and
pretending to be from a legitimate organisation (such as the UK Home Office, an education agent or even UKCISA). They demand money (calling it a "fine" for a non-existent immigration problem), and claim that if you do not pay them quickly, there will be damaging consequences (for
example, deportation or cancelling your visa).
Recently UKCISA has had reports of students being targeted by fake calls purporting to be from the Home Office, demanding action or threatening huge fines. They have even created a phone number to call back which sounds as if it is a genuine Home Office number.
Some students become criminals themselves when they allow money from unknown sources to pass through their bank accounts. Read about the dangers of money laundering.
If you think you've been targeted please speak to your International Office at your university or contact Action Fraud to report it.