The president of Zimbabwe, Robert Mugabe, has accused the United States and Britain of a relentless campaign to destabilise and vilify his country.
Mr Mugabe said George Bush had no right to lecture on human rights
Speaking at the United Nations General Assembly in New York, Mr Mugabe criticised George Bush's human rights record and policies on Iraq.
He called for sanctions against Zimbabwe to be lifted.
Earlier Zimbabwean MPs approved a bill which would end foreign ownership of companies operating in the country.
Mr Mugabe described the conflict in Iraq as the "misadventures" of President Bush and former British Prime Minister Tony Blair.
He said Mr Bush had no right to lecture the world on human rights.
"His hands drip with the blood of many nationalities and today with the blood of Iraqis," he said.
"Mr Bush and Mr Brown have no role to play in our national affairs," Mr Mugabe told the General Assembly.
"They are outsiders and should therefore keep out."
Earlier Mr Bush told the assembly that Zimbabwe was suffering under a "tyrannical regime" and the UN should exert pressure on Mr Mugabe to allow greater freedoms.
Mr Mugabe reiterated that regime change in Zimbabwe would not be brought about by outside influence.
He was also critical of the United Nations Security Council, complaining that Africa did not hold a permanent seat or have the power of veto.
Meanwhile critics are saying that Zimbabwe's new Indigenisation and Economic Empowerment Bill could hurt investor confidence in the country.
It aims to ensure at least a 51% shareholding by indigenous black people in the majority of businesses.
The governing Zanu-PF party says the move will empower the poor majority, but opposition politicians say it will only enrich a few powerful individuals.
Zimbabwe is currently experiencing the world's highest inflation and shortages of food, fuel and foreign currency.
Presidential and parliamentary elections are due to be held next year, following South-African-mediated talks between the government and the opposition Movement for Democratic Change.