DENVER -- Colorado's top election official decertified electronic voting machines used in some of the state's largest counties on Monday, including Denver, Arapahoe and Jefferson.

The devices are also used in Pueblo, Mesa and Elbert counties.

Secretary of State Mike Coffman cited security or accuracy problems in the decertified machines.

A number of electronic scanners used to count ballots were also decertified, including a type used by Boulder County.

Coffman said the system had a 1 percent error rate when counting ballots. "So for every 100 ballots we tested, we found there was an error with one of those ballots," Coffman said.

The manufacturers have 30 days to appeal his ruling.

Coffman announced in March that he had adopted new rules for testing electronic voting machines after problems in the November election.

He said at the time that the four electronic voting systems used in all 64 Colorado counties would have to apply for recertification. The four systems are manufactured by Hart InterCivic, Premier Election Solutions -- formerly known as Diebold Election Systems -- Sequoia Voting Systems and Election Systems and Software.

Coffman had also put Denver, Pueblo, Douglas, Montrose and Routt counties on an election watch list for problems in the November 2006 election. Pueblo has since been removed from the list.

Critics of electronic voting say there are no fixes that will work. Al Kolwicz told 7NEWS that with electronic voting, there is no way to know for certain that a vote has been properly counted.

More lawsuits are possible from both the election machine companies and public interest groups opposed to computerized voting.

On Tuesday, Colorado county clerks and members of the General Assembly will convene at 9 a.m. to hear an explanation from Hoffman about the results of the certification process.

Reaction From County Clerks

"This report is really just part of the larger equation for us. Once we feel we have the full picture of what the Secretary of State's report means, we can move forward with choosing our systems and preparing for the 2008 election season," said Denver Clerk and Recorder Stephanie O'Malley.

"Our number one priority is to ensure that anyone who is registered to vote in next year's election gets a ballot and their vote is counted accurately," said Boulder County Clerk & Recorder Hillary Hall.

She and the Boulder County Elections Division staff have already begun reviewing the Secretary's 188-page document detailing the certification process and its findings.

"We need time to review today's findings and to evaluate the impact on Boulder County's voting system," said Hall. "The document released today is an overview of the testing results and we expect to obtain additional information at tomorrow's hearing. Any statement at this point would be premature. We will keep the public informed as we proceed."