In a column in London's Evening Standard, Herbert, who won the British Grand Prix at Silverstone and is fifth in the drivers' championship, said he has been made to look second-rate because his own team withheld information from him.
"I wasn't allowed to look at certain computer figures and graphs taken from Michael's car," he said. "Yet the team still allowed him to look at the graphs and figures taken from my car."
Benetton have signed Jean Alesi and Gerhard Berger from Ferrari for next season, and while Schumacher will join Ferrari in a record deal, Herbert is left searching for a team.
"Until now I have maintained a diplomatic silence over what has happened at Benetton. In a comparison with Michael it has been anything but a level playing field," the British driver said. "I never imagined the focus on the one driver would leave me feeling almost like an outcast. I don't want to come over as a whinger, but I am a quicker driver than my results suggest."
He said he was not given the same support with testing, and mistakes by the pit crew cost him a top-three placing in the Belgian Grand Prix 12 days ago.
Meanwhile in Monza, Damon Hill believes the greater pressure will be on Schumacher in Sunday's Italian Grand Prix. Schumacher's pulsating victory in Belgium was achieved at the expense of a one-race ban, suspended for four Grands Prix, and Hill hopes that could neutralise the Benetton driver's effectiveness.
Hill last night admitted, tongue only partly in cheek, to some disappointment with the stewards' verdict. "In a way," he said, "it would have been good if he had a ban for six races, to the end of the season, but I suppose we'll have to make do with four."
He went on: "It puts the onus on him to clean up his act. I'm encouraged by the action taken against him because everyone wants to see a clean fight for the rest of the year."
Hill, of Williams-Renault, trailing Schumacher by 15 points, is calling for fair play and no repeat of acrimonious title deciders past. The Briton and the German collided in the final race of last season, at Adelaide.
The current contenders remain at odds over the incident. Hill said: "We still have differences of opinion as far as this matter is concerned. He feels he hadn't transgressed but the rules are very clear. I can point to three actual transgressions.
"Firstly, changing his line more times than permitted; two, crowding on a corner; and, three, deliberately having contact with another car."Reuse content