A dedicated anti-poverty campaigner who worked for Oxfam for 30 years has died at the age of 55.

Susie Smith, who had been suffering from cancer for several years, started working for Oxfam when she was 28 and went on to become deputy international director of the charity.

She spent six years in Zambia before coming to Oxford where she played a key role in transforming Oxfam, rewriting the rules of engagement on poverty, recasting Britain's charity laws and supporting the fight against HIV/Aids.

Kevin Watkins, director of the Human Development Report Office of the United Nations Development Programme, said: "Susie was one of the real heroes in the fight against global poverty.

"The vision, humanity and intellectual honesty she showed during a 30-year career with Oxfam changed the world and touched countless lives."

She gave birth to daughter Sarah in 1985 and, having moved to Oxford, embarked on policy research. She published her first book, Namibia: a Violation of Trust (1986), which documented how the British Government was soft in its opposition to apartheid South Africa's illegal occupation of what was then South-West Africa.

Her second book, Front Line Africa (1990), charted the impact of apartheid, debt and unfair trade rules on the lives of ordinary people. It demolished the argument that development charities could, and should, keep politics out of develop- ment.

Oxfam was hauled before the Charity Commission, found guilty of exceeding its charitable mandate and told to behave itself.

But after a few years of stand-off, charity law was interpreted more flexibly, meaning non-government organisations today do not have to worry about mixing politics with development.

Mr Watkins said: "They owe a vote of thanks to Susie for that. One of her greatest attributes was her willingness to step outside the comfort zone. She was uncompromising in addressing the international causes of poverty.

"But she was also brutally honest about the impact of corruption and indifference to the poor on the part of governments in Africa and elsewhere.

"Never renowned for her diplomatic skills, she told it like it was.

"Susie was an inspiration. Clever, thoughtful, articulate, passionate and persuasive, she was everything that one could want in a colleague, and more. In a sometimes cynical development world, her humility, gentleness and dogged unwillingness to embrace received wisdom shone like a beacon.

"But there is so much more that we shall miss: her love of life, her wicked sense of humour, her passion for poetry and gardens, her pink and purple clothes, and her talent for bringing people together.

"Being a mother was a source of joy and happiness in Susie's life; it was her love for Sarah that gave her the will to fight on so courageously for so long."

First diagnosed with cancer in 1997, Ms Smith suffered a recurrence three years ago. After that, she worked tirelessly to develop Oxfam's HIV/Aids programme, especially in southern Africa.

Over the past year, as her illness progressed, she was visibly in increasing pain. That did not stop her undertaking gruelling trips to Angola, Mozambique, Malawi and Zambia.

She was awarded an OBE in 1999.