German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi decried on Thursday the "unjustified" proposal from Vienna to erect a fence at Austria's Alpine border with Italy to stem the flow of migrants into the country.

"We expressed our total opposition to, and, in some ways, our shock over the position that has been taken by our Austrian friends," said Renzi at a joint press conference with Merkel in Rome, calling the plan "mistaken" and "anachronistic."

"I will do all that is possible so that problems are solved in ways other than through border closures," the chancellor added.

The narrow Brenner Pass has become a point of contention between Italy and Austria, as Rome has long complained that parts of northern Europe were allowing southern European nations to bear the brunt of sheltering and taking care of asylum-seekers.

Fuel was added to the fire on Thursday when far-right Austrian presidential candidate Norbert Hofer, speaking to prestigious Italian daily "La Repubblica," compared the two leaders to migrant smugglers bringing people over the Mediterranean in shoddy, overcrowded boats.

"It is a shameful remark that many respectable people in Austria should reflect on," Renzi responded.

By the end of March this year, 14,500 people had already crossed from Libya to Italy, according to the United Nations refugee agency, all before the easiest season for the journey began.

Hofer is set to face a run-off election for the largely ceremonial post against Alexander Van der Bellen, a Green party politician running as an independent. Hofer's far-right Freedom Party of Austria has seen its popularity increase greatly with the rise of the migrant crisis, as with several similar right-wing nationalist parties across Europe.

es/sms (AP, dpa)