Bulgarian prosecutors have launched an investigation into a recent trip to the country by an Australian man alleged to be the gunman who killed 49 people in attacks on two mosques in Christchurch, New Zealand.

The suspected killer, who identified himself as Australian citizen Brenton Tarrant, visited Bulgaria from November 9 to November 15 claiming he wanted "to visit historical sites and study the history of the Balkan country," Bulgaria's chief prosecutor Sotir Tsatsarov said on March 15.

Tsatsarov said the probe would establish if this was "correct or if he had other objectives."

Investigators say the man arrived in Sofia from Dubai on November 9 and hired a car the following day to visit historical sites in ten locations.

He left on November 15 on a flight bound for neighboring Romania's capital, Bucharest, where he hired a car to travel to Hungary, Tsatsarov said.

The Australian had also made a short visit to the Balkans on December 28-30, 2016, traveling by bus across Serbia, Croatia, Montenegro, and Bosnia-Herzegovina.

Bulgarian authorities said they were in contact with authorities in the United States, New Zealand, Australia, the United Arab Emirates, Serbia, and Montenegro over the matter.

With reporting by AFP