Revealed: the Home Office's secret policy of targeting young Brazilians

The revelation will add another twist to the UK's relations with Brazil, already thrown into crisis by the killing of Jean Charles de Menezes. The policy of targeting Brazilians has been in force since 2003, and might have prevented the killing of Mr de Menezes if it had been enforced sooner, because he exactly fits the type of young Brazilian that immigration officers have been systematically turning away.

But the Home Office was warned in a report last month that there could be Brazilians who wanted to come in as sightseers, but were turned away because they were suspected of being migrant workers posing as tourists.

The report, by the Home Office's independent race monitor, Mary Coussey, was posted on the Home Office website but went almost unnoticed because it appeared in the same week as the first London bomb attacks. It is likely to attract interest now because of the heightened sensitivity of Britain's relations with Brazil and the publicity Mr de Menezes' death has generated in his homeland.

The report revealed that staff at London's airports and at the international train station in Paris had been warned to look out for young men from poor areas of Brazil claiming to be visiting Britain on holiday, because of a high probability that they were seeking work. More than 4,000 were refused permission to enter Britain in 2003. According to a Home Office report, as many as 70 per cent who described themselves as students may have been turned away.

But Mr de Menezes was already in the country before the clampdown began, having arrived in 2002 with permission to stay for three months. He later legally obtained permission to stay on as a student, but when that permission ran out he became what is officially termed an "overstayer".

Britain's Immigration and Nationality Directorate is believed to have received a tip-off from North America that gangs of Brazilian people traffickers were switching their operations to the UK.

But in the drive to keep out illegal workers, immigration officials may have turned away innocent sightseers. More than 8,000 Poles were turned away in 2003, but they gained the right to seek work in the UK when Poland joined the EU last year. Malaysians and Brazilians then became the main targets for suspicious immigration officer.

Ms Coussey's report contrasted the treatment of two visitors, one from the US, the other from Malaysia. The American student originally told immigration officials at Heathrow that he was meeting a friend from the US. Then he claimed he was going to attend a four-month study programme at Cambridge University. A check proved that he was not registered.

About four million Americans visit Britain every year, bringing in a vast amount of foreign currency. A visitor from the US is at least 100 times more likely to be allowed in than someone from Brazil. Despite having apparently lied to officials, this youth was allowed in.

The Malaysian was a tour operator who wanted to board a cross-channel train at Paris and spend four days in the UK on his way to Germany, where his girlfriend lived. He was able to prove that he was employed and had a family in Malaysia. He showed the immigration officers his return ticket, and gave them the details of people he would be staying with. He was refused entry. As he was held up in Paris, his sponsors in the UK and in Germany phoned British immigration officers, offering to vouch for him, but he was still refused entry.

Ms Coussey also reported that she had looked into a sample of eight individual cases of visitors from Brazil who were turned away. She concluded that three "seemed to be justifiable" but five were "more finely balanced".

One Brazilian had arrived at Paris's international train station with a return ticket, a valid hotel booking, a printed itinerary, a guidebook in which he had highlighted all the places he wanted to see, $250 and €300 in cash, and evidence that he had a job in Brazil. But a British immigration officer spotted that his passport was new, implying that this was his first trip abroad, and refused to believe that someone on his salary would pay so much for eight days in the UK.

"I was informed that Gare du Nord Paris was being targeted, because it was wrongly perceived to be easier to gain entry to the UK by rail," Ms Coussey said. "At Heathrow I was told that Brazil has a large educated middle class for whom job prospects were poor. Brazilians had been displaced from seeking work in Canada and the USA."

Ms Coussey has since had a reply from the Home Secretary acknowledging that immigration officers are likely to be "more sceptical" about visitors from certain targeted countries.