The UK's elections watchdog has signalled that any move to hold a euro referendum alongside the next general election could face stiff opposition.

Interviewed by ePolitix.com on the day that the Electoral Commission unveiled plans for a review of election law and procedures, Sam Younger expressed unease at the prospect of combining a referendum on the single currency with any other national election.

"The euro is an issue of major constitutional significance and ought to be separately treated," he said.

"You shouldn't be combining a decision whose advocates and opponents cut across party lines with an election that's being fought on party lines.

"You'd have the confusion for the electorate of two people appearing on a platform on the same day against each other in one set of elections and with each other on a referendum issue."

While he fails to say whether the commission would resist moves to hold a referendum on the same day as a national election, he says that the rationale behind an earlier statement warning against holding a euro poll to coincide with this May's local elections still stood.

"I think we'd want to look at any particular combination that was suggested," he told ePolitix.com.

"But I think you could say that it's pretty clear from that statement we made that we wouldn't like the idea of a major referendum being held at the same time as party-based elections."

The intervention comes amid suggestions that Tony Blair may hold a euro poll to coincide with the next general election. The prime minister, who has clashed with the chancellor over the timing of a referendum, appears determined to press ahead with a poll, even if it costs him his job.

Younger also suggested that future elections will make far greater use of postal ballots, but warned the door should not be closed on traditional voting techniques.

"I think certainly postal voting will be extended. I have some scepticism about whether one wants to go entirely to all-postal, because I think the great thing about postal voting is that although it's opened up opportunities for the electorate, there are still some people who like the option of voting in a conventional polling station," said Younger.

"So I'm a little bit concerned about necessarily shutting off any other option other than the post. But there's no doubt that the electorate has appreciated having all-postal ballots."

The Electoral Commission has unveiled its review of election law, calling for a fundamental review of voter registration.

"Against a background of changes in voting methods, particularly the extension of postal voting and the possibility in the future of internet and other electronic forms of voting, we're looking at two broad areas," said Younger.

"One relates to issues of security and integrity of the system, and the other relates to making sure you appropriately can encourage participation.

"It's fair to say at the moment that the key area which we think needs to be changed is the registration system and then a number of arrangements relating to absent voting in particular and then the form of the ballot paper and the electoral timetable."