Updated:  8:46p.m. ET:  Election officials in six Florida counties are investigating what appears to be "hundreds” of cases of suspected voter fraud by a GOP consulting firm that has been paid nearly $3 million by the Republican National Committee to register Republican voters in five key battleground states, state officials tell NBC. 

But the veteran GOP consultant, Nathan Sproul, who runs the firm, strongly defended his company's conduct, saying it has rigorous "quality controls" and blamed the alleged fraud on the actions of a few "bad apples," workers who were hired to register Republican voters for $12 an hour and then tried to "cheat the system." 

The allegations of suspected voter fraud committed by Strategic Allied Consulting of Tempe, Arizona spread Thursday to counties throughout Florida. At the same time, the Republican National Committee said it had severed its ties to the firm altogether.

"We have heard from supervisors in six counties that they have irregularities in voter registration," said Chris Cate, spokesman for the Florida Department of State, which oversees the state's division of elections.  Although local prosecutors are already investigating the firm's conduct, Cate said state officials were also considering turning the matter over to the Florida Department of Law Enforcement to determine if there was a pattern of misconduct.  

The suspected fraud included apparent cases of dead people being registered as Republican voters, said Paul Lux, the supervisor of elections in Okaloosa County and a Republican. He compared the suspected fraud to the alleged acts of ACORN, the liberal activist group that became the center of a national controversy several years ago.

"It's kind of ironic that the dead people they accused Acorn of registering are now being done by the RPOF" [Republican Party of Florida], Lux said in an interview with NBC News.

In addition to Palm Beach County, where election officials initially reported 106 instances of suspected fraudulent registration forms, officials in Okaloosa, Pasco, Santa Rosa, Lee and Clay counties have also reported instances of possible fraudulent forms submitted by the firm, officials said.

In a statement on Strategic Allied's website, the firm's lawyer said:

"Strategic has a zero tolerance policy for breaking the law. Accordingly, once we learned of the irregularities in Palm Beach County, we were able to trace all questionable cards to one individual and immediately terminated our working relationship with the individual in question. Strategic is committed to following the letter of the law and will continue to cooperate with the Palm Beach County Supervisor of Elections to ensure that this issue is resolved."

Sproul said in a telephone interview that his company has employed between 4,000 and 5,000 people to register Republican voters under its contract with the RNC, including over 2,000 in Florida. The employees are given training on how to register voters, including being required to watch a video instructing them not to register felons. The video also instructs recruiters not to "modify or falsify voter registration forms."

"No matter what quality controls you have there are always going to be bad actors in any large scale operation," Sproul said.

Sproul, who has long worked for the GOP, also criticized Florida and national Republican officials for dumping him.

"They're trying to get the distraction behind them," he said about the RNC's action. 

Sean Spicer, communications director for the RNC, said Strategic Allied Consulting had been retained by the RNC and state Republican parties to register new Republican voters in five key battleground states.

But Spicer said that the party's relationship with the firm-- which has been paid $2.9 million by the RNC so far this year, according to federal elections records -- has now been terminated in light of alleged voter fraud linked to one of the firm's employees that was reported this week to Florida prosecutors by election officials in Palm Beach County. 

"We've made it clear we're not doing business with these guys anymore," said Spicer.  "We've come out pretty strong against this kind of stuff -- and we have zero tolerance for this."

Strategic Allied’s parent firm, Lincoln Strategy Group, also headed by Sproul, has been paid about $80,000 by the Romney campaign to conduct "field consulting," according to election records. Asked for comment, Sarah Pompei, a spokeswoman for the Romney campaign, said by email:  "We used this vendor for signature gathering services during the primary but have not used them since 2011."

Besides Florida, Strategic Allied Consulting was hired to register GOP voters in Nevada, North Carolina, Colorado and Virginia. Spicer said it was the only firm hired by the RNC to conduct voter registration. In the case of Nevada, he said, the RNC was paying the firm directly. In the other four states, the firm was being paid by state parties with the funds reimbursed by the RNC. 

The allegations involving voter fraud by the GOP consulting firm are a new twist in the national controversy over the threat posed by voter fraud and the impact of new state laws passed by Republican controlled legislatures to combat it. While Republican officials have repeatedly accused Democratic groups such as ACORN of fraudulently registering voters in the past, the new dispute over what happened in Palm Beach--  involving the registration of Republican voters -- appears to be one of the first to have led to a criminal inquiry in this year's election.

Christine Weiss, a spokeswoman for the Palm Beach State Attorney's Office, told NBC News Thursday that the alleged voter fraud by a Strategic Allied Consulting employee is "currently being investigated" by prosecutors in her office after it was brought to the attention of prosecutors on Monday by Palm Beach election supervisor Susan Bucher.

Out of 304 Republican voter registration forms recently dropped off by a Strategic Allied employee at a small "satellite office" of the Palm Beach  elections office, 106 were flagged as potentially fraudulent-- including "a lot" with "similar looking" signatures and others with apparently phony addresses, Susan Bucher, the Palm Beach elections supervisor, said in an interview.

Among the suspect home addresses were those that matched a gas station in Miami, a medical building in Boca Raton and a Land Rover automotive dealership in Palm Beach County, she told NBC News.

Bucher said she called in the political director for the Palm Beach Republican Party and the GOP official agreed that the registration forms were a problem. She then took the forms to the Palm Beach County State's Attorney's office on Monday and requested the investigation.

In a statement issued Tuesday night, Mike Grissom, executive director of the Florida Republican Party, said: "When we learned today about the instances of potential voter registration fraud that occurred in Palm Beach County, we immediately informed the Republican National Committee that we were terminating the contract with the voter registration vendor we hired at their request because there is no place for voter registration fraud in Florida."

Sproul has been previously accused of suppressing Democratic voter turnout, throwing away registration forms, and manipulating ballot initiatives. His firms -- formerly Sproul & Associates, Lincoln Strategy, and Strategic Allied Consultants -- had previously worked for RNC voter registration efforts during the campaigns of George W. Bush and John McCain. In 2004, Democratic Senators Leahy and Kennedy sent a letter to then Attorney General John Ashcroft requesting that he "launch an immediate investigation into the activities of Mr. Sproul and his firm." But the request did not lead to any criminal charges against Sproul.