At least 50 Rolling Stones fans were turned away from the Capital Centre on Tuesday night and a similar number last night after oficials told them their tickets to the rock group's sold-out concert were counterfeit.

District of Columbia police said yesterday that all had purchased their ticket through a Washington Post classified asvertisement, one of hundreds that offered the tickets at prices well above their $17.50 face value. Police said they are investigating the incident.

Nick Hanks, one of those stopped with bogus tickets Tuesday night, said he and three friends purchased them for $50 each from a man, believed to be in his 20s, in a Cleveland Park apartment. "We were all wary of the guy's character. He didn't seem like a Rolling Stones freak," said Hanks, a University of Maryland graduate student.

"He said that he waited in line and just got extra tickets," said Priscilla McPherson, who was with Hanks when the tickets were purchased. "We all had funny feelings about it but nobody spoke up. The tickets . . . even had a Wendy's hamburger ad on the back."

Gary Handleman, director of administrative operations for the Capital Centre, said that ticket takers began to spot the bad tickets 25 minutes after the doors opened at 6:35 p.m. Tuesday. "They were pretty good copies, but our ticket takers are pretty good, too," he said.

Handleman said that the fakes were printed on heavier paper than the genuine tickets and the printing was out of line.

"It was tough," said Hanks. "It's not the money, it was just that we had come so far and we were really up for this," he said.