BBCThe government is investigating after BBC reports revealed some migrants are being advised to make false claims they are gay or a victim of domestic abuse in order to stay in the country.
No 10 said there were "robust safeguards" to make sure claims are "rigorously and fairly assessed".
The prime minister's spokesman said the Home Office and the regulator, the Immigration Advice Authority, were working to ensure "anyone potentially abusing our immigration system is held accountable".
Opposition parties have called for a complete overhaul of the asylum system to prevent false claims.
A BBC investigation has uncovered how migrants whose visas are due to run out are being given fake cover stories and instructed in how to obtain fabricated evidence, including supporting letters, photographs and medical reports.
In some cases, law firms and advisers are charging thousands of pounds to advise migrants how they can claim to be gay and in fear for their lives if they return to Pakistan or Bangladesh, in order to apply for asylum.
The BBC has also discovered how some migrants are exploiting rules brought in by ministers to help genuine victims of domestic abuse to secure permanent residence more quickly than through other routes, such as asylum.
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