Azerbaijan, the Caspian nation best known for its caviar and petroleum, is buying Australian government bonds, joining a growing list of sovereign investors acquiring debt Down Under in a trend that has seen the Aussie dollar labelled a potential safe-haven currency by the International Monetary Fund.

The former Soviet republic's $33bn sovereign-wealth fund - the State Oil Fund of the Republic of Azerbaijan, or Sofaz - said it quietly started buying Australian bonds in July, at a time when market data show the Aussie dollar gained 3.4% in value over the month.