An Iranian lesbian who fled to Britain after her girlfriend was arrested and sentenced to death faces being forcibly returned after losing the latest round in her battle to be granted asylum.

The case of Pegah Emambakhsh, 40, comes a day after The Independent reported on the growing public outcry over the plight of a gay Iranian teenager who fears he will be executed if he is deported to Iran.

Both cases have provoked international protests against Britain and led to calls for an immediate moratorium on the deportation of gay and lesbian asylum-seekers who fear they will be persecuted in Iran.

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More than 60 MEPs have signed a petition asking Gordon Brown to reverse the decision on Mehdi Kazemi, 19, who escaped to the Netherlands after the Home Office refused him asylum last year. His case is still before Dutch judges who will decide this month whether he should return to Britain where he faces deportation to a country which has already executed his boyfriend.

Gay rights group claim there are dozens more cases of gay and lesbian asylum-seekers living in Britain in fear of persecution and facing harsh punishments if forced to return to Iran.

Ms Emambakhsh came to the UK in 2005 fearing for her life after her partner had been arrested by Tehran police. Iranian gay rights groups have reported that that partner is in custody under sentence of death by stoning. Speaking through her asylum representative in Sheffield yesterday, Ms Emambakhsh said: "I will never, never go back. If I do I know I will die."

Under the Iranian Islamic Punishment Act, lesbians found guilty of sexual relations can be sentenced to 100 lashes. But, for a third offence, the punishment is execution.

Ms Emambakhsh narrowly avoided deportation in August last year but only after her local MP, Richard Caborn, and other parliamentarians persuaded the Government to allow her to stay while further legal avenues of appeal were explored. She says she was already on the way to Heathrow when she learnt of her last-minute reprieve. But last month the Court of Appeal turned down her application for permission for a full hearing. Ms Emambakhsh said yesterday that she was "very disappointed" by the ruling but planned to apply for a judicialreview at the High Court. The Home Office has also agreed to consider fresh legal representations on her behalf.

The Liberal Democrat MEP Baroness Ludford has written to the Home Secretary to request her urgently to review the case of Mehdi Kazemi. Lady Ludford, the party's European justice spokesperson and a member of the European Parliament's Gay and Lesbian Rights Intergroup, said: "Jacqui Smith must recognise and act on the real threat of persecution and even execution which Mr Kazemi would face if he was to be deported to Iran."

Mehdi Kazemi, 19, came to London to study English in 2004 but later discovered that his boyfriend had been arrested by the Iranian police, charged with sodomy and hanged.

In a phone conversation with his father in Tehran, Mr Kazemi was told that, before the execution in April 2006, his boyfriend had been questioned about sexual relations he had with other men and under interrogation had named Mr Kazemi. Fearing for his own life if he returned to Iran, Mr Kazemi claimed asylum in Britain. Late last year, his claim was refused. Terror-stricken at the prospect of being deported, he made a desperate attempt to evade deportation by fleeing to the Netherlands where he is being detained amid a growing outcry from campaigners.

In turning down Ms Emambakhsh and Mr Kazemi's asylum applications, the Home Office has said that, provided Iranians are discreet about their homosexuality, they will not be persecuted. But Omar Kuddus, of Gay Asylum UK, demanded that Britain follow the example of the Netherlands and Germany in imposing a moratorium on all deportations involving gay and lesbian Iranians. He asked: "How many more young Iranians have to die before the British Government takes action?"

The chief executive of the Border and Immigration Agency, Lin Homer, said: "Our country guidance for such cases is published and is considered as amongst the best in the world. We have expert case workers who make decisions on such cases and there are further avenues through the courts. When and if a court decides that we should look at a case again we will do that."