Abbott's comments to the London Times are the strongest given yet by a major foreign leader on the Scottish independence debate, and follow on calls from US President Barack Obama to keep the union intact.
"It's hard to see how the world would be helped by an independent Scotland," said Abbott.
"I think that the people who would like to see the break-up of the United Kingdom are not the friends of justice, the friends of freedom, and the countries that would cheer at the prospect... Are not the countries whose company one would like to keep".
Scotland goes to the polls on September 18 to decide whether to break away from the 307-year-old union.
Obama last month backed the union, saying: "If it ain't broke, don't fix it."