British democracy could be undermined by moves to use electronic voting in elections, warns a report.
The risks involved in swapping paper ballots for touch screens far outweigh any benefits they may have, says the Open Rights Group report.
It based its conclusions on reports from observers who watched e-voting trials in May's local elections.
The group called for a halt to e-voting until it is reliable, easy to oversee and has proven its integrity.
Observers acting for the ORG scrutinised local elections in England which tried out e-voting as well as Scottish elections using electronic counting systems to tally votes.
What the observers saw led the ORG to express "serious concerns" about e-voting and whether it should be used local and national elections. In England, e-voting systems using kiosks, laptops, touch screens and mobile phones have been tried.
The ORG's main objection was that e-voting was currently a "black box" system which stopped voters seeing how their votes were recorded or counted.
This, said the ORG, made oversight of elections "impossible" and left them open to "error and fraud".
The report criticised the lack of a rigorous certification scheme to ensure that the hardware and software used in e-voting schemes were free from vulnerabilities and protected the integrity of the voting system.
It also called for usability testing to ensure that those who e-voting schemes were designed to serve - the elderly and housebound - could use them easily.
The report said more work was also needed on the e-counting systems used in the elections and said in some cases the new systems were abandoned in favour of a manual count.
The counts by machine or hand sometimes produced very different results, pointed out the report.
The problems with e-counting systems overturned the initial support that many voting officers had for the new hardware, said the report.
The Group said it was a serious mistake to accept the conveniences of e-voting while ignoring how they might undermine confidence in voting as a whole.
In light of the problems it uncovered, the ORG said a halt should be called to e-voting trials to ensure that their shortcomings are addressed before they are more widely used.
The "significant lack of agreement" among computer scientists about how secure and reliable voting is via the net or mobile led the group to say: "considerable academic research and debate must be pursued before further e-voting trials can be considered".
In response to the ORG report, the Ministry of Justice said: "We welcome input to the debate on electoral pilot schemes, and electoral modernisation in general.
"However, it is the Electoral Commission's statutory responsibility to evaluate and report on electoral pilot schemes and we look forward to the publication of their official reports in August, to which we will respond."