Nine people have been convicted of running an immigration fraud linked to English tests for foreign students.

Hundreds of non-EU citizens are said to have got student visas after paying fake "sitters" to take language exams on their behalf.

Four people were found guilty at Southwark Crown Court of immigration law offences. A fifth pleaded guilty and four others were convicted earlier.

The trials resulted directly from a BBC Panorama investigation.

To qualify for a visa in the UK, overseas students must demonstrate a certain competence in English.

The then-government-accredited Test of English for International Communication (TOEIC) examines reading, listening, grammar and vocabulary.

It involves a written and oral section and a separate multiple-choice question paper.

Image caption Total Care directors Talal Choudhury and Shaheen Ahmed were seen in the footage

However, in 2014 Panorama revealed that the TOEIC exams at two test centres were being taken on behalf of foreign visa applicants in exchange for cash.

The programme secretly filmed fake "sitters" at Eden College International (ECI) in east London and at the Universal Training Centre in Watford.

Undercover footage in which entire rooms of registered candidates stepped aside so that exams could be taken by people who spoke better English was shown at the trials.

The plotters were equally brazen when it came to a multiple-choice paper - the secret filming showed an invigilator simply reading out the answers for candidates to copy.

The oral and written test answers were recorded on computers. However, ETS, the US company that set and marked the exam, failed to detect that the same voices appeared numerous times under different names.

Image caption Exam candidates at one college gathered alongside their "sitters" as the tests took place...

Image caption ...while at another site some snoozed as they waited in an adjacent room

The court heard that "proxy sitters" were paid £50 for each exam they took.

Clients were promised a "guaranteed pass" for £500, about three times the official exam fee.

The footage from the Universal Training Centre showed candidates waiting in a separate room while their tests were faked.

Spreadsheets recovered from the two test centres listed more than 1,000 candidates who had passed the exam fraudulently. Beside their names another column - headed "proxy", "assistant" or "pilot" - listed the people who sat the test for them.

The defendants in the Southwark Crown Court case were connected to ECI and Studentway Education, an immigration agency in Southall.

ECI staff member Mohammed Hasan, Total Care London directors Talal Choudhury and Shaheen Ahmed, and former Studentway employee Harinder Kumar were found guilty of conspiring to facilitate breaches of immigration law.

Immigration agent Chowdhury Baker Habib pleaded guilty to the same charge.

Total Care helped stage the exams at the test centre.

Image caption Fassiuddin Mohammad was tried in his absence and sentenced to five years

It can also now be reported that in May, four employees of Universal Training Centre and Bright Consultant Services - an immigration centre based in East Ham and Wembley - were convicted of similar offences at an earlier trial in May.

UTC director Zahid Hafeez received a five-year prison sentence but one of the accused fled abroad to escape justice.

Bright Consultant Services director Fassiuddin Mohammad was tried in his absence and sentenced to five years.

Two other Bright Consultant Services staff, Faiza Noreen and Sameer Shaikh, received suspended sentences.

The Home Office stopped accepting TOEIC pass certificates for visa applications, and launched a nationwide investigation, following Panorama's revelations.