Mr Adams had been refused a visa in 1996 because of his links with the IRA.

Australia's immigration minister, Philip Ruddock, said that since then there had been significant progress towards peace in Northern Ireland.

"In light of these developments," said Mr Ruddock, "I have decided to exercise my discretion to not refuse Mr Adams a visa."

He added: "Australia looks to Mr Adams and to Sinn Fein to shoulder their full responsibility with all other parties to ensure rapid progress in the peace process."

Mr Adams said the visit was important because of the large Irish community that lives in Australia.

"Ironically enough, the very reason given for me not being allowed into Australia was the very reason given for people being sent to Australia over the centuries ... that was that we were of bad character," Mr Adams told ABC Radio from Dublin.

"So it's an interesting piece of history that that Catch 22 has turned on its head. But I would like to think that the Australian Government will see its way to assisting in the peace process by allowing it to be under discussion."

An Irish community leader, Dennis O'Flynn, welcomed the decision, noting that Adams had already been received in the White House and is also accepted in Britain.