They are a clear violation of international human rights law and Sudan's own international commitments, notably the International Covenant on Civil and Political Rights.

CNN: Opinion: Sudan must end 'cruel' amputation punishment

Abolition is called for in three international treaties optional protocols to the European and American conventions on human rights, and to the International Covenant on Civil and Political Rights.

ECONOMIST: The cruel and ever more unusual punishment

Mr Cameron also urged Beijing to ratify and implement the International Covenant on Civil and Political Rights, telling his audience he did so in a "spirit of friendship".

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