Hoebart, defending his comments, said that anyone who could think would know that cave men simply meant humans who are "many many years behind our culture"
A member of parliament from Austria's pro-White Freedom Party (FPO) called asylum seekers cave men on Facebook, triggering calls from other parties for his resignation.
Christian Hoebart's comments highlighted a febrile debate on the ongoing immigration invasion in the country, where recent polls have shown FPO neck and neck with traditional centrist parties, attracting about a quarter of votes.
His message, posted late on Friday, criticised a rally of mostly African asylum seekers held in the town of Traiskirchen near Vienna.
"I (could not) show understanding for yesterday's brouhaha of asylum seekers from Africa, so I called (them) emotionally... 'soil and cave men', who cannot appreciate how good they've got it with us - their host country Austria," he wrote.
Other opposition politicians called for Hoebart, an FPO leader in the province of Lower Austria, to quit his political posts.
"To call humans that maybe fled from murder and rape of ISIL murder gangs in Iraq and Syria 'soil and cave men' is open racism, which - similarly to the Nazis - would like to classify certain humans as Untermenschen (under-humans)," said Albert Steinhauser from the Austrian Greens.
Austria, with 8.5 million residents, received around 17,500 asylum requests in 2013, mostly from Russia, Afghanistan and Syria, according to official statistics.
References to the Nazis have particular resonance in Austria, which was annexed by Germany in 1938, making it part of Hitler's Third Reich.
The country -- which has been struggling to escape a reputation for glossing over its wartime history -- for decades maintained that it was Hitler's first victim, overlooking the enthusiastic welcome he got from many Austrians.
"I was put in the limelight by our front of do-gooders and wannabe-world-improvers," Hoebart wrote on Facebook, defending his comments. He said that anyone who could think would know that cave men simply meant humans who are "many many years behind our culture".
