Clare Short campaigned against landmines
Leading aid agencies have paid tribute to Clare Short following her resignation as international development secretary, saying she will be a "tough act to follow".
Oxfam's Adrian Lovett said she had won international development a high public profile and had been a "passionate and powerful champion" of the cause.
And Christian Aid's Andrew Pendleton said Ms Short had managed to change the way people felt about the issue.
Catholic Agency for Overseas Development (Cafod) director Julian Filochowski, speaking from Brussels, said Ms Short had taken international development to "the heart of government".
Despite their regret at Ms Short's departure, the groups said they were looking forward to working with her successor, Baroness Amos, who has been the government's spokeswoman on international development in the House of Lords.
Mr Lovett, who is Oxfam's director of campaigns and communications, said Ms Short had championed international development in the Cabinet, with the British public and on the international stage.
He said: "With her leadership, the aid budget has grown substantially and the UK has played a key role in lobbying for increased debt relief and improved terms of trade for developing countries."
Mr Lovett said it was important that the groundwork carried out by Ms Short was now built on.
One in three people don't know where their next meal is coming from - Clare cared about that
Andrew Pendleton said: "I don't think anybody quite thought about international development and an international development secretary in quite the same way before Clare Short arrived in the job, so that's a tough act to follow."
Cafod's international division head Beverley Jones said: "She's put a strong poverty focus into international development and doubled the aid budget.
"She revisited some of the most intractable conflicts like Sierra Leone, Congo and Sudan, putting her energies behind looking for peaceful solutions."
Jessica Woodroffe, ActionAid's Head of Policy, said: "Clare Short's weaknesses were her strengths. She took no prisoners.
"One in three people don't know where their next meal is coming from. Clare cared about that and continually reminded her colleagues that the needs of poor people must be at the centre of debates on aid."
Daleep Mukarji, director of Christian Aid, added that he was pleased with the appointment of Baroness Amos.
Richard Lloyd, director of Landmine Action, an umbrella group that campaigns against the use of landmines, said he had been very disappointed at the resignation.
Over the last few months her position has become increasingly untenable
He said Ms Short was respected because she had been able to bring together various organisations on the landmine issue.
"Her sheer force of personality and her vision of what needed to be done got things done, got people together," he said.
Shadow international development secretary Caroline Spelman said Ms Short had been sidelined in the run-up to war in Iraq.
Ms Spelman said: "Clare Short was successful at raising the profile of
international development, but over the last few months her position has become increasingly untenable."
She said that by being publicly at odds with the government on a number of issues, Ms Short had weakened her position and that of her department.
Staff at the Department for International Development also paid tribute to Ms Short following her resignation on Monday.
John Hudson, who works in the policy division at the department, said: "Clare was a powerful advocate for development.
"She was strong, enthusiastic and determined. She really cares seriously about development."