· Report says 10 states not ready for electronic vote · Scientist hacks into new polling machine on TV

Six years after the emergence of the now infamous "hanging chad" in the 2000 presidential elections, monitoring groups warn that technological glitches and hackers could throw next month's mid-term elections into chaos.

With polling day less than two weeks away, a report this week by electionline.org, a non-partisan organisation, anticipates problems at the ballot box in as many as 10 states.

"Machine failures, database delays and foul-ups, inconsistent procedures, new rules and new equipment have some predicting chaos at the polls at worst, and widespread polling place snafus at best," the report says.

The mid-term elections will be the first national test of new voting procedures introduced in the aftermath of the 2000 election debacle in Florida, when it took a month of court challenges and recounts of punch-card ballots before George W Bush was declared to have won the state, and became president.

In the wake of that fiasco, Congress allotted $3.8bn (£2bn) to the states to modernise voting lists and replace the old-style punch-card systems with electronic voting machines by early 2006.

Election officials in more than 30 states opted for touch-screen voting machines that use a series of prompts to guide voters through the ballot. But the new machines have merely reawakened the old anxieties about miscounted votes and deliberate fraud.

In many states, voters will be casting their votes electronically for the first time. The officials at the polling stations may be equally inexperienced, and because such workers are typically elderly and retired, critics say they may be particularly poorly equipped to deal with any technological problems.

Those concerns crystallised last month, when a Princeton professor of computer science, Edward Felton, and two colleagues managed to hack into a new electronic voting machine without detection and install a virus that could alter vote counts - and go on to infect a wider network of machines.

The exercise, which Mr Felton repeated on television, took about a minute to complete. The manufacturers of the voting machine said Mr Felton had ignored newer software and security measures that safeguard against hacking.

However, vote monitoring organisations and computer scientists have grown increasingly wary about the new voting machines, especially those that do not leave a paper trail in case it is needed for future verification.

The rollout of the new systems has been far from smooth. In Maryland, earlier this autumn, voting was delayed for hours across an entire county because election officials forgot to bring in the electronic cards that activate the touch-screen machines.

During the 2004 elections in North Carolina, polling officials failed to notice the constant flashing of a warning light on the voting machine indicating that its memory was full. More than 4,400 votes were lost as the result of their inattention. In that same election year, a software error in Texas polling stations led to a vote overcount, with 100,000 more votes registered than had been cast.

The Electionline study predicts 10 states could face similar fiascos this time around because of computer security, inexperienced or elderly poll workers, and a network of new regulations meant to prevent illegal immigrants from voting.

Over the period of the past six years, the number of states requiring voters to show identification before they are given a ballot has risen from just 11 states to 24 states this year.

The study said it anticipated problems in Arizona, Colorado, Connecticut, Florida, Indiana, Maryland, New York, Ohio, Pennsylvania and Washington state.