Alois Mannichl, 52, was found slumped in the porch of his house in Fürstenzell near Passau, late on Saturday afternoon, having been attacked with a knife.
Local newspaper Am Sonntag reported Mannichl answered his front door to a tall skinhead at around 5:30 pm on Saturday.
The man said something along the lines of “Greetings from the national resistance,” and said, “You leftist pig cop, you won’t trample on the graves of our comrades any more,” before stabbing Mannichl in the stomach with a 12-centimetre knife.
He then threw the knife away in the garden and ran to a waiting car in the nearby street and was driven away.
Although Mannichl was seriously wounded, he was able to speak to colleagues who arrived on the scene and give them a description of the man who he said he had not seen before.
He was described as beefy, about 1.90 metres tall and with a tattoo or birthmark. His Bavarian accent had an Austrian influence in it, Mannichl said.
Mannichl was operated on in hospital and is said to be out of danger, although seriously wounded.
Investigators said they were looking for the attacker within Bavarian fascist groups.
Bavarian state interior minister Joachim Herrmann called the attack cowardly, devious and brutal at a press conference on Sunday.
He said that if the attack really have been carried out by a far-right extremist, it would indicate that neo-Nazi violence had reached a completely new dimension.
Far-right resentment in the region against the police reached a high point this July after the authorities ordered that the grave of a former neo-Nazi functionary be opened so that a Nazi flag that had been buried with the coffin, be removed.
The local far-right extremist NPD party had accused the police chief of making the group feel harassed on November 16 as they marked the defeat of Nazi Germany at the end of World War II.