Leaders of thoroughbred racing scrambled yesterday to reassure fans shaken by allegations of tampering on last Saturday's Breeders' Cup wagering.

The allegations -- that a computer engineer working for a tote company may have electronically altered a bet after the race had been won -- could devastate a sport increasingly dependent on fans betting from afar through computers.

The $3.1 million payoff to a Baltimore man has been frozen as investigators probe the circumstances of his wager. On Thursday, the tote company that processed the bet fired a software engineer it said may be involved and turned over evidence to police.

The National Thoroughbred Racing Association, a self-styled league office for the sport, yesterday announced the creation of a task force on computer security. Also, Santa Anita Racecourse, where a $1 million guaranteed Pick Six will be offered today, announced it had added cameras and guards to its tote rooms where wagers are tallied.

"Whatever the outcome of the current investigation, we must stay focused on the overriding priority of keeping faith with the fans and customers who support our game and industry through legal wagering," said NTRA commissioner Tim Smith.

Smith has long stressed the importance of interactive television, computers and other new media to the future of racing. Last year, more than 85 percent of the $14.6 billion wagered on thoroughbreds came from fans somewhere other than the track where the race was run. If confidence is lost in the electronic backbone of this wagering, it could severely hamper racing.

"It is a big part of the future. Getting it right from the standpoint of computer security is critically important," Smith said at a teleconference yesterday.

Smith said he does not know of any other case where someone has been shown to have breached computer security in thoroughbred betting. But that may not be enough for fans who were already suspicious of late-changing odds and other peculiarities of wagering in the computer era.

"Me and my friends have suspected there has been manipulation for years. It just seems that the odds are doing funny things," said Bob Rivera, a mortgage banker and devoted horse player from Los Angeles.

He said he would be more reluctant to bet through electronic means as a result of the Pick Six scandal.

"I think the integrity is very much a question now," he said.

Douglas L. Florence Jr., a security expert and former director of surveillance for the Mirage casino in Las Vegas, said he knew of no computer cheating involving horse racing. But there have been cases where thieves have managed to tamper with keno, slot and bingo machines, he said.

"When you have a machine that determines the winners this can happen," said Florence, a regional vice president for API Services Inc. of Windsor, Conn. "Usually it is a glitch or a weakness in the system."

Investigators suspect the Breeders' Cup Pick Six may have been tampered with by someone who exploited the flow of data between computer systems that processed the bets.

Under current protocol used by all the tote companies, a bet made on a Pick Six -- in which the gambler attempts to predict the outcome of six consecutive races -- is recorded in the system that takes the wager. Only after the fourth race are the identities of the customers who correctly bet those races, and have a chance to win, forwarded to the main computer system. It then tracks the bets through the final two races.

The idea is not to swamp the system with data. But the delay in sending the bets creates an opportunity for mischief. Someone with the proper computer access could change a bet after the race but before the bet is forwarded to the main system.

"We need to change the transactional procedures," said Donald Groth, chairman of Catskill Off-Track Betting Corp. in Pomona, N.Y., which processed the Pick Six bets under investigation.

He noted, however, that the system detected a problem before the money was paid.

Marc Brawner, a forensic computer examiner, said a properly built system should contain enough cross-checks to leave investigators with a clear idea of what happened in the Breeders' Cup case.

For example, separate records should be available for the bets made and the time they were made or altered, said Brawner, with Kroll Inc. of New York. "If their systems are set up properly, there should be a trail to follow," he said.

"It's quite possible that an engineer may have access to the data but there should be a record. There are two or three points along the way that there should exist a record of the bet," he said.

Delaying the movement of betting data between sites creates a point of "vulnerability," he said.

The New York racing board also has been asked by racing officials in that state to examine suspicious Pick Six wagers made during August's meet at Saratoga Racecourse.

Stacy Clifford, a spokeswoman for the agency, declined to comment on any investigation.

"We'll look at anything and everything that might be relevant," she said.

Serving on the NTRA security task force will be Breeders' Cup president D.G. Van Clief Jr., Thoroughbred Racing Association executive vice president Chris Scherf, Thoroughbred Racing Protective Bureau president Paul Berube, Equibase chairman Alan Marzelli, handicapper and author Jim Quinn, president of the Association of Racing Commissioners Lonny Powell, and North American Association of Pari-Mutuel Regulators executive director Frank Lamb.

"Like any other business making electronic financial transfers, we need to get the best possible procedures and practices," Smith said.