Australian Prime Minister John Howard has ordered the country's cricket team to pull out of a scheduled tour of Zimbabwe in September.
Mr Howard said Robert Mugabe was a "grubby dictator"
He said the tour would be an "enormous propaganda boost" to Zimbabwe President Robert Mugabe, a "grubby dictator".
The Australian team was due to play three one-day internationals.
Pressure had been building on the team not to go ahead with the tour to the strife-torn African nation. Australia will not be fined for not touring.
Mr Howard said on Australia's ABC television: "The government through the foreign minister has written to Cricket Australia instructing that the tour not go ahead."
He added: "We don't do this lightly."
The Mugabe regime is behaving like the Gestapo towards its political opponents
Australian Prime Minister
The prime minister said the government could use its power over the players' passports if Cricket Australia did not abide by his decision.
"Whilst it pains me both as a cricket lover and as somebody who genuinely believes these things should be left to sporting organisations... it leaves me with no alternative," said Mr Howard.
The head of Cricket Australia, James Sutherland, said the body was committed to help Zimbabwe cricket develop and would now look at holding the matches in a venue outside the country.
The likely venue is South Africa, where a Twenty20 World Cup series will be held later in the year.
"We are obliged to do what we can to help Zimbabwe cricketers and we could help them by playing somewhere else," Sutherland said.
"We are discussing with the government where we could play Zimbabwe at a neutral venue."
Mr Howard has long been a critic of Mr Mugabe's government but this was his strongest condemnation yet, says the BBC's Nick Bryant in Sydney.
"The Mugabe regime is behaving like the Gestapo towards its political opponents," Mr Howard said.
"I have no doubt that if this tour goes ahead it will be an enormous boost to this grubby dictator."
In 2005, New Zealand refused visas for Zimbabwe's cricketers - preventing them from proceeding with a tour to their country.
Australia last played Zimbabwe in a World Cup warm-up game
But this is the first time a government has acted to stop its players travelling to Zimbabwe.
Cricket Australia had been reluctant to cancel its September tour to Zimbabwe because that would have made it liable to pay a minimum $2m fine levied by the sport's international governing body, the International Cricket Council (ICC).
However, an ICC statement indicated Cricket Australia would not be fined if the government took the matter out of its hands.
Zimbabwe's ambassador to Australia, Stephen Chiketa, said last week that politics had no place in sport and that banning the tour would hurt the development of cricket in his country.
"You have young players in Zimbabwe who want to emulate great cricket players in Australia," he told Australia's Seven television network.
"Take your politics somewhere else."