A group of “neo-Nazis” beat up two twin brothers and menaced them with a knife in front of a Lower East Side bar Saturday morning when they took offense to an “anti-fascist” sticker on one of the men’s cellphone cases, police said.

The beatdown happened when the brothers, both 27-year-old Columbia graduate students, noticed the large group of “skinheads” hanging inside one of their usual haunts called Clockwork on Essex Street and decided to head for the exits around 12:30 a.m.

On the way out the door, they ran into a group of smokers outside who noticed the sticker on one of their phones reading “New York City Anti-Fascists.”

“One of the guys … sees [my brother’s] phone, grabs it and starts screaming, ‘I know what the f— that means, I know what the f— that sticker is, you need to get the f— out of here,’” said one of the victims, who asked to remain anonymous.

“He throws the phone on the ground and they just start jumping us right in front of the bar.”

The brothers were pummeled by about six or seven men — some who were using brass knuckles — and dressed in matching vests with “211 Crew” patches, a white supremacy gang, police said. The brothers tried to run away from their attackers but were chased down Essex Street and then Hester Street before the group caught up to them and continued the beating, cops said.

“One of the guys pulled a knife on my brother first and starts slashing at him. Then the guy with the knife starts coming over to me … His buddy grabs him and I guess at that point they all decide to run off.”

Officers in an undercover police car that happened to be driving by spotted the two bloodied men standing on the sidewalk while trying to call 911 and asked them what was going on.

They were able to point out one of the suspects lingering around the scene and police quickly grabbed him.

He was identified as 29-year-old John Young and was charged with assault, grand larceny, menacing, criminal mischief and possession of a weapon, cops said.

“I didn’t think something like this could happen. This is crazy,” one of the victims said. “I didn’t think they would be so brazen as to patronize a bar in Manhattan like that. I go there all the time and never felt a bad feeling.”

The men suffered cuts and bruises to their faces and bodies. One brother required five staples to close a wound on his head while the other received two staples for a head wound at a nearby hospital.