Two Australian aid workers in Yugoslavia have been charged with spying.

The two men, Steve Pratt and Peter Wallace, were detained more than a month ago at the border near Croatia and accused of using the Australian aid agency, CARE, as a cover for organising and gathering intelligence.

Soon after his arrest, Mr Pratt appeared on state television to say he had been involved in acquiring intelligence.

His colleagues said he was acting under duress, and the Australian government has described the charges as preposterous.