
The May 2007 Election Report (PDF) examined the use of electronic systems in English and Scottish elections in May, and found serious problems with the use of the technology.
ORG, which was given official electoral observer status, claimed that the counting of votes was impossible to confirm, and that the technology was immature and rushed in.
"ORG concludes that, given the problems observed and the questions remaining unanswered, it cannot express confidence in the results declared in the areas observed," said the report.
"Given these findings, ORG remains opposed to the introduction of e-voting and e-counting in the UK."
The report found problems in the computer technology used to register votes, flaws in the software to count the votes and little official oversight as to how votes are counted.
Election counts using paper ballots are personally overseen by candidates and electoral agents but this is not possible with electronic voting.
The short timescale for the introduction of such systems meant that counting and voting systems were rushed in with as little as six months' notice and were not adequately tested.
The Electoral Commission said in a statement: "The timetable was tight from the beginning of the project, and delays in the production of technical requirements, assessing the proposals, contract negotiation and the production of statutory orders caused further delay.
"This resulted in insufficient time for the suppliers and local authorities to implement the systems in a structured and methodical manner.
"As a result, it was not possible to provide an appropriate level of quality assurance throughout the process and in relation to all aspects of operation."
Despite the findings, the UK government plans to introduce further electronic voting, including by text message, in time for the next general election.