The three - Gary Blanchard, Joseph Pettijohn and John Dixon - were jailed for six months with labour after being found guilty of possessing firearms and trying to load them on an aircraft at Harare airport.

Mr Chinamasa said the sentences had induced "a sense of shock and outrage in the minds of all right-thinking people."

"The leniency of the sentences constitutes a betrayal of all civilised and acceptable notions of justice and of Zimbabwe's sovereign interests," he said.

The Attorney-General said the crimes committed by the three men had been "trivialised" and that he would appeal to the Supreme Court for a heavier sentence.

Special powers

Mr Chinamasa is a member of the Zimbabwean cabinet and some observers say his statement is a further sign of tensions between the state and the judiciary.

During the course of the trial President Mugabe intervened to invoke special powers preventing a relaxation of the stringent security conditions under which the three men were being kept.

In his judgement, High Court Justice Ismael Adam said he had taken into account reports that the men had been tortured after their arrest and had been subjected to "inhuman treatment" while awaiting trial.

Throughout the trial, the men have declared their innocence and said they had the weapons for self-protection while working as missionaries in the Democratic Republic of Congo.