Speaking from the human rights organisation's International Council Meeting in Mexico, Amnesty International Secretary General Irene Khan said:

'The brutal murder of Sergio Vieira de Mello is yet more proof that people who serve humanity and defend human rights are easy targets in a world in which national security has trumped human security.

'Human rights, the international community and all those who promote peace and justice in Iraq are under attack.

'Only when human rights take centre stage and inform our approach to world security, will we stop these hideous crimes from occurring again,' she said. 'The next few days in Iraq will be critical. We can establish the genuine security needed to breach this perilous chasm or we can revert once again to the tactics which breed the unrest and discontent at the root of this violence. What further evidence do we need that eroding the principles which underpin human rights leads only to escalating insecurity and death?

'Sergio Vieira de Mello the man has been killed, but his ideals and message remain alive,' declared Ms Khan as she stated that grief has only strengthened Amnesty International's resolve for action.

Ms Khan cautioned that Mr Vieira de Mello's murder has put at stake the fundamental human rights of the Iraqi people. 'Iraq must be a building site for human rights - it must not be allowed to become a wasteland.'

Paying tribute to Mr Vieira de Mello, a close friend of many years, Ms Khan said: 'He was a man of action and conviction, exuding all that is positive and passionate in life.'

Ms Khan called for the perpetrators of the attack to be apprehended and brought to justice but added: 'His death must not become a pretext for a witch-hunt nor lead to widespread abuse of human rights.'