In 2000, the 28-year-old Saudi was admitted on a student visa to study in Oakland.

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The Yemeni government has confirmed that Mr Abdulmutallab lived in the country between August and December, after obtaining a visa to study Arabic there.

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According to the ministry's statement, AbdulMutallab had obtained a visa to study Arabic at a language institute in Yemen where he had previously studied.

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That's why with us, if you're good at your subject, can speak English and have been offered a place on a course at a trusted institution - you will be able to get a visa to study here.

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They show only formal visa approvals for work or study.

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All students from outside the EU wishing to study in the UK need to have their visa application sponsored by education establishments which are licensed by the government.

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The Home Office said this was a "long standing" agreement - but stressed Brazilian nationals entering the UK for other purposes, such as work or study, must ensure that they have the appropriate visa.

BBC: UK Border Agency

The system is in addition to extra laws imposed last month, when the INS introduced new measures requiring any foreigner wishing to study at a US university to have an approved student visa before taking any courses.

BBC: US to track foreign students