An A-grade student from one of the poorest areas in the country has had an offer of a place on a prestigious medical course withdrawn after admissions officers ruled that a spent criminal conviction meant he could not be trusted to become a doctor.

Majid Ahmed, 18, from Little Horton in Bradford, lost an appeal against the decision by Imperial College London to bar him from its medicine degree, a move that youth justice charities labelled discriminatory and MPs called unfair.

Ahmed was convicted of burglary in 2005 and ordered to serve a four-month referral order for community service. His conviction is spent and he has moved schools, volunteered with disability charities and won four A grades at A-level.

Imperial offered him a place for study this academic year, an offer which was withdrawn after he wrote to tell the college of his conviction. The university said the decision had been made to uphold trust in the medical profession.

Ahmed appealed, presenting evidence from his school, charities and doctors with whom he has undertaken work experience, but last week the appeal was turned down.

Ahmed said: "I had the place and then it was taken off me. I am overwhelmed by anger that I have let something like this affect my life. I'm a kid who has grown up surrounded by violence and drugs. Give me a chance and I'll show the universities that I'm not a bad guy. I won't risk their reputation."

Last night Bill Rammell, the minister for higher education, refused to comment on the case, saying that student selection was a matter for individual universities.

However, he added: "Universities should not turn away talented individuals ... when convictions are spent or when they have made positive steps to change their lives and improve their futures."

The decision comes as ministers consider new strategies to encourage more people from the poorest backgrounds to go to the elite universities. Imperial is ranked sixth in the country for medical degrees. Only 4% of its intake is made up of students from the poorest backgrounds.

The General Medical Council yesterday confirmed that people can still become doctors if they have a criminal record. A candidate could be barred if thought to pose a risk, but evidence including references would be considered.

Paul Cavadino, chief executive of Nacro, the crime reduction charity, said: "This is an appalling way to treat a young man with the potential to become an able and dedicated member of the medical profession. This kind of discrimination can have devastating consequences for individuals."

Stephen Williams, the Liberal Democrat spokesman on universities, said: "To be rejected in this way, having apparently been open and honest with the university, seems very unfair."

Imperial said: "The college requests information on a candidate's 'unspent' convictions only ... medicine, however, is focused on preparing students for a career that has particularly demanding requirements. Medical practitioners hold a position of responsibility in society, and must often deal with vulnerable people. The public must have confidence in the integrity and probity of its doctors.

"Imperial believes that by carrying out and acting upon the CRB [Criminal Records Bureau] checks of potential medical students, it plays an important role in helping to uphold this trust."